F`]] @@@ @@@@33 @fsU]] EN DB ] #*   ~x Dando19746]Harris-Warrick1996^ Kopell1993fW Marder1999XNonnotte1990W Selverston1979C:\DOCUME~1\FARZAN\LOCALS~1\Temp\PubMed (NLM).tmp- Selverston1979. Selverston19809 Selverston1980 Selverston1981 Selverston1982 Selverston1982: Selverston1982; Selverston1983< Selverston1983= Selverston1983 Selverston1984S Selverston1984T Selverston1984M Selverston1984/ Selverston1984 Selverston1985> Selverston19850 Selverston1986? Selverston1986 Selverston19871 Selverston19872 Selverston1987 Selverston19883 Selverston19884 Selverston19885 Selverston19886 Selverston19888 Selverston1989 Selverston1989 Selverston1990 Selverston1990 Selverston1991 Selverston1991 Selverston1992 Selverston1992 Selverston1992 Selverston1993 Selverston1993 Selverston1994 Selverston19949W Selverston1995 Selverston19957 Selverston1995 Selverston1996X Selverston1997 Selverston1997A Selverston1997Y Selverston1998& Selverston1998 Selverston1999$ Selverston1999% Selverston1999 Selverston2000+ Selverston20000B Selverston2000 Selverston2001 Selverston20026 Selverston2003k Selverston2003D Sen1996 Sen1998E Sharman2000F Sharp1992p Sharp1993G Sharp1993H Sharp1993o Sharp1994 Sharp1995I Sharp1996MSi-Liang1977 Siegel19939 Siegel1994J Siegel1994KSigvardt1982LSigvardt1982{Sigvardt1997Sillison1986N Simmers1987R Simmers1988S Simmers1988P Simmers1990 Simmers1991h Simmers1993 Simmers1994 Simmers1994f Simmers1995O Simmers1995Q Simmers1995g Simmers1997Z Simmers1998[ Simmers1998^ Simmers1998 Simmers1998 Simmers1998y Simmers1998\ Simmers1999d Simmers1999e Simmers19999 Simmers2000 Simmers2000z Simmers2000] Simmers2001 Simmers2001) Simmers2002{ Simmers2002 Simon2001 Simon2003 Simon2005 Sirchia1987y Siwicki1986 Skarbinski19988[ Skiebe1994L Skiebe19959 Skiebe19977 Skiebe19999T Skiebe1999W Skiebe1999Z Skiebe2000U Skiebe2001Y Skiebe2002\ Skiebe2002V Skiebe2003X Skiebe2003] Skilleter1986_ Skinner1993^ Skinner1994I Skinner1996 Sosa20040 Soto19979* Soto-Trevino1998w Soto-Trevino1999` Soto-Trevino2001a Spirito1975bSpruston1991 Stein2000Q Stein2004- Stewart2003c Storch1989l Storm1995 Strassburg2004d Suh1988eSullivan1978g Suthers1981f Suthers19848Sweedler200207Sweedler20030h Swensen2000i Swensen2000 Swensen2001j Swensen2001 Szelier1999 Szucs2000B Szucs2000 Szucs2001k Szucs2003. Szuts1999Takemoto1986l Tanner1995 Taveras1983r Tazaki1986t Tazaki1986m Tazaki1988s Tazaki1990o Tazaki1991u Tazaki1991J Tazaki1992 Tazaki1992n Tazaki1993p Tazaki1993q Tazaki1994v Tazaki1997v Tazaki1997w Tazaki2000w Tazaki2000y Terio1993# Thirumalai19998 Thirumalai2002 Thirumalai2002x Thirumalai20027 Thirumalai2003 Thirumalai2003 Thirumalai2003y Thoby-Brisson1998z Thoby-Brisson2000{ Thoby-Brisson2002|Thompson1982` Thoroughman2001 Thuma2000} Thuma2002~ Thuma2003 Thuma2003 Tierney1992 Tierney1997 Tierney1999 Torres2001 Torres2001" Tresch20000# Truman1996! Truman19989" Truman20010 Tsien1996 Tsung1992 Turrigiano1989 Turrigiano1990 Turrigiano1990 Turrigiano1991 Turrigiano1992_ Turrigiano1993 Turrigiano1993 Turrigiano1994 Turrigiano1994K Turrigiano1995 Turrigiano1995q Turrigiano1996 Turrigiano1996 Turrigiano1999Van Weel1970 Van Wormhoudt1994 Varona2000B Varona20000 Varona2001 Varona2001 Vedel1974 Vedel1977 Vedel1977 Vedel1979 Vincent1996 Volkovskii2000;Wadepuhl19838<Wadepuhl19838=Wadepuhl19838Wadepuhl1987 Wagner1986K Wales1976 Wales1976 Walton19755 Warshaw1976 Weaver2002 Weaver2003 Weaver2003 Weaver2003) Webb20000X Weckwerth2003Weigeldt1993 Weimann1989 Weimann1990 Weimann1991 Weimann1992 Weimann1992 Weimann1992 Weimann1992 Weimann1993 Weimann1993 Weimann1994z Weimann1997 Weimann1997Wilensky2003Williams1907 Willms1997 Willms1997i Withers1998\Wollenschlager2002 Wood2000 Wood20010 Wood2002 Wood2004 Wootton1995_ Wu19909 Xu20040 Yang1986 Yaple2001IYarotsky2003 Yonge1924 Zarrin1994 Zhang1992 Zhang1994 Zhang1995 Zhang1995 Zhang1997J Zhang2003 Zhang2003 Zhang2003 Zhang2004 Zilberstein2002 Zilberstein2002) Zipfel2000 Zirpel1993Simmers1999e Simmers19999 Simmers2000 Simmers2000] Simmers2001 Simmers2001) Simmers2002 Simon2001 Simon2003 Sirchia1987y Siwicki1986 Skarbinski19988[ Skiebe1994L Skiebe19959 Skiebe19999T Skiebe1999W Skiebe1999Z Skiebe2000U Skiebe2001Y Skiebe2002\ Skiebe2002V Skiebe2003X Skiebe2003] Skilleter1986_ Skinner1993^ Skinner1994I Skinner1996* Soto-Trevino1998w Soto-Trevino1999` Soto-Trevino2001a Spirito1975bSpruston1991Q Stein2004- Stewart2003c Storch1989d Suh1988eSullivan1978f Suthers19848Sweedler200207Sweedler20030 Swensen2001 Szelier1999 Szucs2000B Szucs2000 Szucs2001. Szuts1999Takemoto1986 Taveras1983J Tazaki1992 Tazaki1992y Terio1993# Thirumalai19998 Thirumalai2002̈ Thirumalai20027 Thirumalai2003 Thirumalai2003 Thirumalai2003` Thoroughman2001 Thuma2000" Tresch20000# Truman1996! Truman19989" Truman20010 Tsien1996_ Turrigiano1993K Turrigiano1995q Turrigiano1996 Varona2000B Varona20000 Vedel1974 Vedel1977 Vedel1979 Vincent1996 Volkovskii2000;Wadepuhl19838<Wadepuhl19838=Wadepuhl19838Wadepuhl1987 Wagner1986K Wales1976 Walton19755 Weaver2002) Webb20000X Weckwerth2003Weigeldt1993̉ Weimann1992 Weimann1992 Weimann1992 Weimann1992 Weimann1993z Weimann1997 Willms1997̺ Willms1997i\Wollenschlager2002 Wood20010_ Wu19909 Yaple2001IYarotsky2003 Zarrin1994 Zhang1992 Zhang1997J Zhang2003 Zilberstein2002) Zipfel200002  T!"& )'.-1$%34(+5/82<0@9BC>FH=E?KMGNQRPJSXZ[\V]`abcO_ghijdmspqtuwz{}kr|xy AuthorspJournals tKeywords o                                D  Abarbanel, H.Abarbanel, H. D. Abbott, L. F. Abbott, L.F. Abel, B. Abele, L.G. Adams, S.R. Adelman, G. Agricola, H. Akoev, G. N. Albert, J. Allen, J.A. Alspector, J. Altman, J. An, W. F.Anderson, D.T.Anderson, W. W.Anderson, W.W. Ando, F. Arbib, M.A.Archavsky, Y.I. Armstrong, D.Arshavsky, Y. I. Ascher, P. Atwood, H. L. Atwood, H.L. Auerbach, A. Ayali, A. Ayers, J. Ayers, J. L. Ayers, J.L. Baar, E. Bal, T Bal, T. Baldwin, D.Baldwin, D. H. Baldwin, D.H. Balkema, A.A. Barazangi, N. Barker, D. L. Barker, D.L. Barker, P.L. Baro, D. J. Baro, D.J. Baro, D.L. Barth, G. Bartos, M. Bedrov, Y. A.Beenhakker, M. P.Belanger, J. H. Beltz, B. Beltz, B. S. Bem, T. Benson, J.A. Bianchi, A.L. Bidaut, M.Billimoria, C. P.Birmingham, J. T.Bittner, G. D. Blanck, J. Blitz, D. M. Bohm, H. Booth, J.D. Booth, V. Borner, J. Bose, A. Bucher, D. Buchholtz, F. Buchman, E. Buchner, K.Budelli, R. W. Buisson, A. Bullock, T.H. Bush, B.M.H.Cabirol-Pol, M. J. Cain, S. D. Caine, E.A. Calabrese, R.Calabrese, R. L.Caldwell, R.L.Callaway, J. C. Calvin, W. H. Calvin, W.H. Camhi, J. Cardi, P. Carew, T. Carew, T.C. Carlton, C.E.Casasnovas, B. Casey, M.Castelfranco, A. M. Cattaert, D.Cazalets, J. R.Cazaletz, J.R.Cervates-Peres, F. Chabaud, F. Chang, E. S. Chanussot, B. Cherny, E. Chiba, C. Christie, A.Christie, A. E.Claiborne, B. J.Claiborne, B.J. Clarac, F. Clark, M. C. Clason, T. A.Cleland, T. A. Cleland, T.A. Clemens, S. Cohen, A.H. Cohen, L. Cohen, N. Cole, C.L.Coleman, M. J. Combes, D.Coniglio, L. M.Coniglio, L.M. Cooke, I. M. Cooke, I.M. Coombs, E.G. Corey, S.Cottrell, G.W. Cournil, I. Cowan, J.D. Cowan, N. G.Creutzfeldt, O. Dall, W. Dando, M. R. Dando, M.R. Davis, K. R. de Vente, J. Degos, L. Deitmer, J.W.DeKlotz, T. R.Devanit-Saubie, M. Dever, J. J. Dever, T. E.DiCaprio, R. A. Dick, O. E.Dickinson, P. S.Dickinson, P.S. Dietel, C. Dindle, H. Dircksen, H. Doshi, M. Dreger, M. Duce, I.R. Durbin Dybek, E.Edwards, D. H., Jr.Edwards, J. M. Eeckman, F.H.Eeckmann, F.H. Eigg, M. H. Eisen, J. S. Eitner, E. El Manira, A. Elsner, N. Elson, R. Elson, R. C.Epstein, I. R. Epstein, I.R. Epstein, S. Erber, J Erber, J. Evans, B. Evers, J. F. Ewald, D.A. Ewer, J. Factor, J.R.Fairfield, W. P. Falcke, M. Farnham, J. Faumont, S. Felder, D.L.Felgenhauer, B.E. Fenelon, V.Fenelon, V. S.Fentress, J.C. Ferrell, W.R. Fickbohm, D. Flamm, R. Flamm, R. E. Flamm, R.E.Fleischer, A.G. Florkin, M. Fraser, M. French, L. French, L. B. Friedi, M. Friend, B. J. Friesen, J.A. Frost, W. N. Ganeshina, O. Garzino, V. Gassie, D. V.Gassie, D. V., Jr. Gassie, D.V. Geffard, M. Gibson, R. Gielen, S. Giles, C.L.Gisselmann, G. Glaser, D.A. Glasser, S. Glowik, R. M.Goaillard, J. M.Godleski, M. S. Gola, M. Goldberg, D.Goldman, M. S. Golomb, D. Golowasch, J.Golowasch, J.P.Gossard, J.-P. Govind, C. K. Govind, C.K. Goy, M. F. Graubard, K.  !""&& &'')').1.-.-111111$%%$$$$111%%333+(4++5555555/////82222<<<<<00@9@9@B@B@@@BBCC>C>FFH=====??E?H=====?===KKMMMMGMGMMKMMGGGNNNNGNNQQQQQQQPJJJQRRPPRJSSSSSXlLobsters/*physiology94202013D>Elson, R. C. Panchin, Y. V. Arshavsky, Y. I. Selverston, A. I.haMultiple effects of an identified proprioceptor upon gastric pattern generation in spiny lobstersPIAnimal Electrophysiology Ganglia, Invertebrate/physiology In Vitro Lobsters/*physiology Mastication/physiology Mechanoreceptors/*physiology Motor Neurons/physiology Peripheral Nerves/physiology Proprioception/*physiology Stomach/anatomy & histology/innervation/*physiology Support, U.S. Gov't, P.H.S. Tooth/innervation/physiologyr1. Using deafferented preparations of the stomatogastric nervous system of spiny lobsters (Panulirus interruptus), we stimulated the central soma of the Anterior Gastric Receptor neuron (AGR) and analyzed sensorimotor integration in the gastric central pattern generator during rhythm production. 2. Driving AGR to spike tonically at lower frequencies (10-20/s) accelerated the gastric rhythm, while higher frequencies (> or = 30/s) suppressed it. 3. Shorter spike trains in AGR evoked phase-dependent resetting of the gastric rhythm. Repetitive trains could entrain rhythms to both longer and shorter cycle periods. Some pattern-generating effects are consistent with effects upon the lateral gastric neuron, an influential member of the gastric mill network. 4. AGR affected the burst intensity of many of the gastric neurons in specific, complex ways. Some power-stroke motor neurons were excited because AGR activated excitatory, premotor interneurons (E cells). However, AGR also activated parallel, seemingly inhibitory inputs, whose mechanism remains unclear. Still other effects on motor neurons may be mediated partly by synaptic interactions within the network. J Comp Physiol [A] 1994 174i3a 317-29  0tActa Zootaxonomica Sin Adv PhysiolAJNR Am J Neuroradiol$Am Report R J Comm Inland Fish Am ZoolAmer ScientistAnn N Y Acad SciAnn Sci Nat ZoolAnnu Rev Neurosci Annu Rev Pharmacol ToxicolAnnu Rev PhysiolArch Int Physiol BiochimAust J Mar Freshw ResBehav Brain Sci Bioessays Biol Bull Biol CybernBiologie in inserer Zeit. Biophys JBr J PharmacolBrain Behav Evol Brain ResBrain Res BullBrit J Exp BiolC R Acad Sci ParisC R Acad Sci Paris D Can J Zool$Cell Mol Biol (Noisy-le-grand)Cell Tissue ResComp Biochem PhysiolComp Biochem Physiol C Curr BiolCurr Opin NeurobiolCurr Opin NeuronbiolDev Genes EvolEur J NeurosciForma et FunctioGene IEEE Trans Circuits SystemsIEEE Transactions, SMCInvert NeurosciJ Anat Physiol J Comp NeurolJ Comp PhysiolJ Comp Physiol A85J Comp Physiol A Neuroethol Sens Neural Behav PhysiolJ Comp Physiol [A]J Comput Neurosci J Crust Biol J Exp BiolJ Exp Mar Biol Ecol J Exp Zool J Gen PhysiolJ Histochem Cytochem J Morph J MorpholJ Neural Networks J Neurobiol J Neurochem J NeurocytolJ Neurophysiol J NeurosciJ Neurosci Methods J PhysiolJ Physiol (Lond)J Physiol (Paris)J Physiol Paris Life SciMar Behav Physiol Mar Biol Mem Fac Fish (Kagoshima Univ)Microsc Res Tech Mol Neurobiol Mol Pharmacol Nat Neurosci NatureNaturwissenschaften Network Neural Comp Neural Comput Neural NetwNeurocomputing Neuron Neurosci Lett Neuroscience Neurosignals New Scientist Peptides Pflugers ArchPhil Trans Roy Soc B("Philos Trans R Soc Lond B Biol Sci@ pyloric constrictor (PY) synapse and increasing PY input resistance. As previously reported, graded inhibition was enhanced at these two LP output synapses. We conclude that DA can differentially modulate the spike- evoked and graded components of synapses between members of a central pattern generator network. At the synapses we studied, actions on the presynaptic cell predominate in the modulation of graded transmission, whereas effects on postsynaptic cells predominate in the regulation of spike-evoked IPSPs.J Neurophysiol 1998794 2063-9&Ayali, A. Harris-Warrick, R. M.db\Monoamine control of the pacemaker kernel and cycle frequency in the lobster pyloric network@9Animal Biogenic Monoamines/*physiology Dopamine/pharmacology/physiology Efferent Pathways/physiology Female Ganglia, Invertebrate/*physiology Lobsters/*physiology Male Nerve Net/*physiology Neurons/drug effects/physiology Octopamine/physiology Pylorus/*innervation Serotonin/physiology Support, U.S. Gov't, P.H.S.The monoamines dopamine (DA), serotonin (5HT), and octopamine (Oct) can each sculpt a unique motor pattern from the pyloric network in the stomatogastric ganglion (STG) of the spiny lobster Panulirus interruptus. In this paper we investigate the contribution of individual network components in determining the specific amine-induced cycle frequency. We used photoinactivation of identified neurons and pharmacological blockade of synapses to isolate the anterior burster (AB) and pyloric dilator (PD) neurons. Bath application of DA, 5HT, or Oct enhanced cycle frequency in an isolated AB neuron, with DA generating the most rapid oscillations and Oct the slowest. When an AB- PD or AB-2xPD subnetworks were tested, DA often reduced the ongoing cycle frequency, whereas 5HT and Oct both evoked similar accelerations in cycle frequency. However, in the intact pyloric network, both DA and Oct either reduced or did not alter the cycle frequency, whereas 5HT continued to enhance the cycle frequency as before. Our results show that the major target of 5HT in altering the pyloric cycle frequency is the AB neuron, whereas DA's effects on the AB-2xPD subnetwork are critical in understanding its modulation of the cycle frequency. Octopamine's effects on cycle frequency require an understanding of its modulation of the feedback inhibition to the AB-PD group from the lateral pyloric neuron, which constrains the pacemaker group to oscillate more slowly than it would alone. We have thus demonstrated that the relative importance of the different network components in determining the final cycle frequency is not fixed but can vary under different modulatory conditions.'\VSection of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, USA.10415000http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10415000 http://www.jneurosci.org/cgi/content/full/19/15/6712 http://www.jneurosci.org/cgi/content/abstract/19/15/6712 J Neurosci 199919156712-22.12177147 205/ Pt 18 2002 SepgrlThe locust frontal ganglion: a central pattern generator network controlling foregut rhythmic motor patterns2825-32The frontal ganglion (FG) is part of the insect stomatogastric nervous system and is found in most insect orders. Previous work has shown that in the desert locust, Schistocerca gregaria, the FG constitutes a major source of innervation to the foregut. In an in vitro preparation, isolated from all descending and sensory inputs, the FG spontaneously generated rhythmic multi-unit bursts of action potentials that could be recorded from all its efferent nerves. The consistent endogenous FG rhythmic pattern indicates the presence of a central pattern generator network. We found the appearance of in vitro rhythmic activity to be strongly correlated with the physiological state of the donor locust. A robust pattern emerged only after a period of saline superfusion, if the locust had a very full foregut and crop, or if the animal was close to ecdysis. Accordingly, haemolymph collected at these stages inhibited an ongoing rhythmic pattern when applied onto the ganglion. We present this novel central pattern generating system as a basis for future work on the neural network characterisation and its role in generating and controlling behaviour.'d]Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.*#Ayali, A. Zilberstein, Y. Cohen, N.("22166698 0022-0949 Journal Article J Exp Biollehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12177147y (nv78048123$Ayers, J. L. Selverston, A. I.:3Synaptic control of an endogenous pacemaker network2+Action Potentials Animal Ganglia/physiology Lobsters/*physiology *Membrane Potentials Motor Neurons/*physiology Nerve Net/*physiology Nervous System/*physiology *Nervous System Physiology Neural Inhibition *Periodicity Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiologyay1. The present study consists of an analysis of the coordinating effects of monosynaptic EPSPs and IPSPs on the discharge of the endogenous pacemaker neurons which drive the pyloric motor system of the spiny lobster. The experiments were performed on isolated nervous systems. 2. An analysis of the characteristic phase response curves to both classes of input (fig. 1) shows that the pyloric oscillator possesses the necessary characteristic for entrainment: i.e. a periodically varying sensitivity to synaptic drive. 3. By repetitive stimulation of either input at frequencies near the endogenous frequency of the PD slow wave, it was possible to entrain the discharge of the pacemaker system to the cyclic stimulus (figs. 2b and 3b). The pyloric discharge tends to occur at different characteristic phase relations in response to the two inputs (figs. 2c and 3c), which reflect features of the corresponding phase response curves (fig. 1). 4. It is argued that the periodic sensitivity of these neurons to synaptic input reflects interactions between the synaptically induced currents and the endogenous currents which underlie the slow wave.a 1977 J Physiolc734e 453-61 Using Smart Source Parsing$Ayers, J.L. Selverston, A.I. 1979voMonosynaptic entrainment of an endogenous pacemaker network: A cellular mechanism for von Holst's magnet effectJ Comp Physiol 129 5-1784113825"Ayers, J. Selverston, A. I.XQSynaptic perturbation and entrainment of gastric mill rhythm of the spiny lobsterleAnimal Electric Stimulation Evoked Potentials *Gastrointestinal Motility Lobsters/*physiology Motor Neurons/physiology Nervous System/physiology Nervous System Physiology Neural Inhibition Pylorus/innervation Stomach/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiology *Synaptic Transmission->8The gastric mill rhythm of the lobster stomatogastric ganglion was perturbed with short trains of synaptic input from the inferior ventricular nerve (IVN) through fibers. The stimulus was delivered randomly for phase-response curve analysis or repetitively to examine entrainment. The responses depend on the phase of the stimulus in the endogenous rhythm. The stimulus may alter the internal coordination of the motor pattern. Stimuli that occur during a lateral gastric nerve- anterior lateral nerve-E-neuron (LG-GM-E) burst perturb the burst internally and produce a prolonged LG-GM-E burst, while those that occur during the silent interval between LG-GM-E bursts may evoke a triggered LG-GM-E burst. Spontaneous, prolonged, and triggered LG-GM-E bursts differ in their internal structure as well as the order of burst onsets and offsets. The intercalated triggered LG-GM-E burst delays the occurrence of the subsequent spontaneous LG-GM-E burst, thus strongly resetting the rhythm. These resetting effects have been formalized by phase-response curve analysis. Over limited constraints, cyclic IVN stimuli can entrain the rhythm. Repetitively delivered IVN stimuli have parametric effects on the rhythm that mask the predictive value of phase-response curve analysis for the determination of the phase relations during entrainment.J Neurophysiol 1984511h 113-25"Bal, T. Nagy, F. Moulins, M. 1988d]The pyloric central pattern generator in crustacea: A set of conditional neuronal oscillatorsJ Comp Physiol 163715-727"Bal, T. Nagy, F. Moulins, M. 1990leControle des proprietes neuronales: son importance dans la flexibilite d'un reseau chez les crustacesArch Int Physiol Biochim Bal, T 1991Mecanismes cellulaire impliques dans la reconfiguration fonctionnelle des reseaux neuronaux stomatogastriques des crustaces: Analyse electrophysiologique et pharmacologique par photodissection in situ Bordeaux, France L'Universite de Bordeaux I Ph.D.D94238365"Bal, T. Nagy, F. Moulins, M.\UMuscarinic modulation of a pattern-generating network: control of neuronal propertiesuAnimal Dose-Response Relationship, Drug Ganglia, Invertebrate/cytology/physiology Lobsters Male Membrane Potentials Motor Activity/*physiology Muscarine/*metabolism Nerve Net/drug effects/*physiology Neurons/drug effects/*physiology Oscillometry Oxotremorine/pharmacology Parasympathomimetics/pharmacology *Periodicity Pylorus/*innervation/physiology Support, Non-U.S. Gov't Synapses/physiology p jThe aim of this article is to investigate the cellular mechanisms underlying cholinergic modulation of the pyloric network in the stomatogastric ganglion (STG) of the Cape lobster Jasus Ialandii. Bath application of the muscarinic agonists muscarine, oxotremorine, and pilocarpine on the STG activates a rhythmic pattern from a quiescent pyloric network. The mechanisms of this modulation were investigated on individual pyloric neurons isolated both from synaptic interactions within the network (by photoinactivation of most of the presynaptic neurons and pharmacological blockade of the remaining synapses) and from central inputs (by a sucrose block of the input nerve). All three muscarinic agonists activated bursting and plateau properties of all the neurons comprising the pyloric network. The activation was dose dependent, and was blocked by the muscarinic antagonists atropine, pirenzepine, and scopolamine. The oscillatory behavior triggered by the muscarinic stimulation was specific to each type of pyloric neuron. The isolated neuron AB had the shortest oscillation period and depolarizing phase. The constrictor neurons (LP, PY, IC) were the slowest oscillators, and only oscillated upon hyperpolarizing current injection. Under muscarinic modulation, the individual bursting activities of the isolated pyloric neurons were of the same type as their activities when isolated from the network but modulated by central inputs (Bal et al., 1988). The VD neuron is an exception since it was a rapid oscillator in the latter situation and became a slow oscillator when modulated by a single muscarinic agonist. To determine the relative importance of the muscarinic-dependent bursting properties of the individual pyloric neurons in the operation of the intact network, a progressive reconstruction of the synaptic circuitry was attempted. We found that under certain conditions of muscarinic modulation a new composite pacemaker could be created, composed of the electrically coupled VD, AB, and PD neurons. This can result in the generation of new pyloric patterns that were very sensitive to the membrane potential of individual network neurons. The data also confirmed that, in a rhythmic "pattern-generating network," the pacemaker role may not be definitely attributed to a given neuron but instead could be assigned to other neurons by modulation of their respective oscillatory capabilities. J Neurosci 199414 5 Pt 23019-35"Baldwin, D.H. Graubard, K. 1995wDistribution of fine neurites of stomatogastric neurons of the crab Cancer borealis: Evidence for a structured neuropiliDS J Comp Neurolu 356355-367- !  T"@:73031920@:Barker, D. L. Herbert, E. Hildebrand, J. G. Kravitz, E. A.0*Acetylcholine and lobster sensory neuronesAcetylcholine/biosynthesis/*physiology Acetylcholinesterase/metabolism Acetyltransferases/analysis Aminobutyric Acids/biosynthesis Animal Atropine/pharmacology Axons/enzymology Carbon Isotopes Choline/metabolism Curare/pharmacology Evoked Potentials Ganglia/enzymology Glutamates/metabolism Iontophoresis Lobsters/*physiology Membrane Potentials Neurons/enzymology Neurons, Afferent/physiology Receptors, Cholinergic Synapses/drug effects *Synaptic Transmission J Physiol (Lond) 1972 226e1' 205-29Barker, P.L. Gibson, R. 1977Observations on the feeding mechanism, structure of the gut and digestive physiology of the European lobster, Homarus gammarus (L.) (Decapoda: Nephropidae)nJ Exp Mar Biol Ecolo26297-324.'Barker, D.L. Kushner, P.D. Hooper, N.K., 1979ZTSynthesis of dopamine and octopamine in the crustacean stomatogastric nervous system Brain Res 161 99-113HBBaro, D.J. Cole, C.L. Zarrin, A.R. Hughes, S. Harris-Warrick, R.M. 1994nhShab gene expression in identified neurons of the pyloric network in the lobster stomatogastric ganglionReceptors and Channels2s193-2050*Baro, D.J. Cole, C.L. Harris-Warrick, R.M. 1996haRT-PCR analysis of shaker, shab, shaw, and shal gene expression in single neurons and glial cellsReceptors and Channels4149-1594f`Baro, D.J. Coniglio, L.M. Cole, C.L. Rodriguez, H.E. Lubell, J.K. Kim, M.T. Harris-Warrick, R.M. 1996aLobster shal: Comparison with Drosophila shal and native potassium currents in identified neuronse( J Neurosci16 1689-17010*Baro, D.L. Cole, C.L. Harris-Warrick, R.M. 1996RLThe lobster shaw gene: cloning, sequence analysis and comparison to fly shaw Gene 170267-270haBaro, D.J. Levini, M.T. Kim, M.T. Willms, A.R. Lanning, C.C. Rodriguez, H.E. Harris-Warrick, R.M.a 1997Quantitative single-cell-reverse transcription-PCR demonstrates that A-current magnitude varies as a linear function of shal gene expression in identified stomatogastric neurons J Neurosci17 6597-6610/rlBaro, D. J. Ayali, A. French, L. Scholz, N. L. Labenia, J. Lanning, C. C. Graubard, K. Harris-Warrick, R. M.zMolecular underpinnings of motor pattern generation: differential targeting of shal and shaker in the pyloric motor systemjdAmino Acid Sequence Animal Axons/physiology/ultrastructure Cell Membrane/physiology/ultrastructure Ganglia, Invertebrate/*physiology Lobsters Molecular Sequence Data Neurites/physiology/ultrastructure Neurons/*physiology/ultrastructure Potassium Channels/analysis/genetics/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/physiologyf`The patterned activity generated by the pyloric circuit in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus, results not only from the synaptic connectivity between the 14 component neurons but also from differences in the intrinsic properties of the neurons. Presumably, differences in the complement and distribution of expressed ion channels endow these neurons with many of their distinct attributes. Each pyloric cell type possesses a unique, modulatable transient potassium current, or A-current (I(A)), that is instrumental in determining the output of the network. Two genes encode A-channels in this system, shaker and shal. We examined the hypothesis that cell-specific differences in shaker and shal channel distribution contribute to diversity among pyloric neurons. We found a stereotypic distribution of channels in the cells, such that each channel type could contribute to different aspects of the firing properties of a cell. Shal is predominantly found in the somatodendritic compartment in which it influences oscillatory behavior and spike frequency. Shaker channels are exclusively localized to the membranes of the distal axonal compartments and most likely affect distal spike propagation. Neither channel is detectably inserted into the preaxonal or proximal portions of the axonal membrane. Both channel types are targeted to synaptic contacts at the neuromuscular junction. We conclude that the differential targeting of shaker and shal to different compartments is conserved among all the pyloric neurons and that the channels most likely subserve different functions in the neuron.'Institute of Neurobiology and Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico 00901, USA. djbaro@neurobio.upr.clu.edu10964967http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10964967 http://www.jneurosci.org/cgi/content/full/20/17/6619 http://www.jneurosci.org/cgi/content/abstract/20/17/6619 J Neurosci 200020176619-30.ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11566511iLFBaro, D. J. Quinones, L. Lanning, C. C. Harris-Warrick, R. M. Ruiz, M.tmAlternate splicing of the shal gene and the origin of I(A) diversity among neurons in a dynamic motor networkhjcAlternative Splicing/*genetics Animal DNA, Complementary/analysis Female Ganglia, Invertebrate/cytology/*metabolism Lobsters/cytology/genetics/metabolism Membrane Potentials/genetics Molecular Sequence Data Movement/*physiology Nerve Net/cytology/*metabolism Neurons/cytology/*metabolism Oocytes/cytology/metabolism Open Reading Frames/genetics Potassium Channels/*genetics/metabolism Protein Isoforms/genetics/metabolism Pylorus/cytology/innervation/physiology RNA, Messenger/isolation & purification Sequence Homology, Amino Acid Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Xenopus/genetics/metabolismtThe pyloric motor system, in the crustacean stomatogastric ganglion, produces a continuously adaptive behavior. Each cell type in the neural circuit possesses a distinct yet dynamic electrical phenotype that is essential for normal network function. We previously demonstrated that the transient potassium current (I(A)) in the different component neurons is unique and modulatable, despite the fact that the shal gene encodes the alpha-subunits that mediate I(A) in every cell. We now examine the hypothesis that alternate splicing of shal is responsible for pyloric I(A) diversity. We found that alternate splicing generates at least 14 isoforms. Nine of the isoforms were expressed in Xenopus oocytes and each produced a transient potassium current with highly variable properties. While the voltage dependence and inactivation kinetics of I(A) vary significantly between pyloric cell types, there are few significant differences between different shal isoforms expressed in oocytes. Pyloric I(A) diversity cannot be reproduced in oocytes by any combination of shal splice variants.While the function of alternate splicing of shal is not yet understood, our studies show that it does not by itself explain the biophysical diversity of I(A) seen in pyloric neurons.'Institute of Neurobiology, Department of Biochemistry-Medical Sciences Campus, University of Puerto Rico, 201 Boulevard del Valle, San Juan, PR 00901, USA. djbaro@neurobio.upr.clu.edu11566511 2001 Neuroscience 1062 419-32 Using Smart Source Parsing |e(%Nervous System/immunology/*metabolismNervous System/metabolismNervous System/physiologyNeural Conduction Neural Conduction/*physiology$Neural Conduction/drug effects0*Neural Conduction/drug effects/*physiology,)Neural Conduction/drug effects/physiology Neural Conduction/physiologyNeural Inhibition Neural Inhibition/*physiology$Neural Inhibition/drug effects0*Neural Inhibition/drug effects/*physiology,)Neural Inhibition/drug effects/physiology Neural Inhibition/physiology Neural Networks (Computer)Neural Pathways Neural Pathways/*physiologyNeural Pathways/chemistry4.Neural Pathways/cytology/immunology/metabolism(#Neural Pathways/cytology/physiology Neural Pathways/drug effects Neural Pathways/embryology Neural Pathways/physiologyNeurites/drug effectsNeurites/metabolismNeurites/physiology("Neurites/physiology/ultrastructureNeuroglia/ultrastructure($Neuromuscular Junction/*drug effects("Neuromuscular Junction/*physiology0*Neuromuscular Junction/cytology/physiology(#Neuromuscular Junction/drug effects4/Neuromuscular Junction/drug effects/*metabolism4/Neuromuscular Junction/drug effects/*physiology4.Neuromuscular Junction/drug effects/metabolism4.Neuromuscular Junction/drug effects/physiology$!Neuromuscular Junction/embryology$!Neuromuscular Junction/physiology41Neuromuscular Junction/physiology/*ultrastructureNeuronal Plasticity$Neuronal Plasticity/*physiology$Neuronal Plasticity/physiology Neurons, Afferent/*chemistry Neurons, Afferent/*physiology0,Neurons, Afferent/*physiology/ultrastructure0*Neurons, Afferent/drug effects/*physiology Neurons, Afferent/physiology0,Neurons, Afferent/physiology/*ultrastructureNeurons/*chemistry$!Neurons/*chemistry/ultrastructure Neurons/*cytology/physiologyNeurons/*drug effects$ Neurons/*drug effects/physiologyNeurons/*metabolism$Neurons/*metabolism/physiology0-Neurons/*metabolism/physiology/ultrastructure("Neurons/*metabolism/ultrastructureNeurons/*pathologyNeurons/*physiology("Neurons/*physiology/ultrastructureNeurons/*ultrastructureNeurons/chemistry Neurons/chemistry/*physiology,&Neurons/chemistry/cytology/*metabolism("Neurons/classification/*physiology<7Neurons/classification/cytology/drug effects/metabolism4/Neurons/classification/drug effects/*metabolism Neurons/cytology/*metabolism Neurons/cytology/*physiology,)Neurons/cytology/drug effects/*metabolism,(Neurons/cytology/drug effects/metabolism Neurons/cytology/physiology$ Neurons/drug effects/*physiology$Neurons/drug effects/physiology41Neurons/drug effects/physiology/radiation effectsNeurons/enzymology0,Neurons/immunology/metabolism/ultrastructure$Neurons/metabolism/*physiology Neurons/metabolism/physiologyNeurons/physiology("Neurons/physiology/*ultrastructureNeurons/ultrastructureNeuropeptides/*analysis@;Neuropeptides/*analysis/isolation & purification/metabolism@;Neuropeptides/*genetics/immunology/isolation & purificationNeuropeptides/*metabolism,&Neuropeptides/*metabolism/pharmacology Neuropeptides/*pharmacology,&Neuropeptides/*pharmacology/physiologyNeuropeptides/*physiologyNeuropeptides/analysis40Neuropeptides/chemistry/*metabolism/pharmacology(%Neuropeptides/chemistry/*pharmacology("Neuropeptides/genetics/*metabolism4/Neuropeptides/genetics/*metabolism/pharmacology4.Neuropeptides/immunology/metabolism/physiology,&Neuropeptides/pharmacology/*physiologyNeuropil/metabolismNeurosciences/historyNeurosecretion  e41Motor Neurons/drug effects/metabolism/*physiology(%Motor Neurons/drug effects/physiology($Motor Neurons/metabolism/*physiologyMotor Neurons/physiologyMouth/*innervationMouth/innervationMouth/physiology Movement0*Movement Disorders/physiopathology/therapyMovement/*physiologyMovement/physiologymulti-phasic rhythms(#Muscarine/*antagonists & inhibitorsMuscarine/*metabolismMuscimol/metabolismMuscimol/pharmacologyMuscle Contraction$Muscle Contraction/*physiology$Muscle Contraction/drug effects0*Muscle Contraction/drug effects/physiology Muscle Contraction/physiology(%Muscle Fibers, Slow-Twitch/physiologyMuscle Fibers/physiology,)Muscle Relaxation/drug effects/physiologyMuscle Tonus/physiology Muscle, Skeletal/innervation Muscle, Smooth/*innervation Muscle, Smooth/innervation,)Muscle, Smooth/physiology/*ultrastructureMuscles/*drug effectsMuscles/*innervation$ Muscles/*innervation/*physiologyMuscles/*physiologyMuscles/drug effects$!Muscles/drug effects/*innervation$Muscles/drug effects/physiologyMuscles/enzymologyMuscles/innervation$Muscles/innervation/*physiology$Muscles/innervation/physiologyMuscles/physiology Mutagenesis, Site-Directed NephropidaeNephropidae/*metabolismNephropidae/*physiology0,Nephropidae/embryology/*growth & development(#Neprilysin/antagonists & inhibitors Nerve BlockNerve Endings/physiologyNerve Fibers/*physiology,&Nerve Fibers/metabolism/ultrastructureNerve Fibers/physiology Nerve Net(#Nerve Net/*drug effects/*physiologyNerve Net/*embryology$ Nerve Net/*embryology/physiology$Nerve Net/*growth & developmentNerve Net/*metabolismNerve Net/*physiology84Nerve Net/anatomy & histology/metabolism/*physiology0*Nerve Net/cytology/*embryology/*physiology$Nerve Net/cytology/*metabolism$Nerve Net/cytology/*physiology0*Nerve Net/cytology/drug effects/metabolism,)Nerve Net/cytology/embryology/*metabolism Nerve Net/cytology/physiologyNerve Net/drug effects("Nerve Net/drug effects/*metabolism("Nerve Net/drug effects/*physiology$!Nerve Net/drug effects/physiology$Nerve Net/metabolism/physiologyNerve Net/physiologyNerve Regeneration0*Nerve Tissue Proteins/*analysis/immunology$!Nerve Tissue Proteins/*metabolism$Nerve Tissue Proteins/analysis,)Nerve Tissue Proteins/genetics/metabolism$ Nerve Tissue Proteins/physiologyNervous System Physiology(#Nervous System/*anatomy & histologyNervous System/*chemistry Nervous System/*embryology Nervous System/*enzymology84Nervous System/*immunology/metabolism/ultrastructure Nervous System/*metabolism Nervous System/*physiologyNervous System/analysis4.Nervous System/anatomy & histology/*physiology0,Nervous System/chemistry/cytology/embryology(#Nervous System/chemistry/embryologyNervous System/cytology(#Nervous System/cytology/*physiology4/Nervous System/cytology/drug effects/physiology<7Nervous System/cytology/growth & development/metabolism,'Nervous System/drug effects/*physiology82Nervous System/drug effects/immunology/*physiologyNervous System/embryology@;Nervous System/embryology/*growth & development/*metabolism(%Nervous System/enzymology/*metabolism(#Nervous System/growth & development4.Nervous System/growth & development/metabolismZY&Cleland, T.A. Selverston, A.I. 1998XQInhibitory glutamate receptor channels in cultured lobster stomatogastric neuronsJ Neurophysiol766 3189-3196981658754.Clemens, S. Combes, D. Meyrand, P. Simmers, J.Long-term expression of two interacting motor pattern-generating networks in the stomatogastric system of freely behaving lobstero Animal Circadian Rhythm Comparative Study Digestive System/*innervation Electromyography Immobilization Lobsters Membrane Potentials Models, Neurological Motor Neurons/*physiology Muscle, Smooth/innervation Nerve Net/*physiology Reaction Time Support, Non-U.S. Gov'tRhythmic movements of the gastric mill and pyloric regions of the crustacean foregut are controlled by two stomatogastric neuronal networks that have been intensively studied in vitro. By using electromyographic recordings from the European lobster, Homarus gammarus, we have monitored simultaneously the motor activity of pyloric and gastric mill muscles for 300% of their mean duration. However, the duration of activity in the lateral pyloric constrictor muscle, innervated by the unique lateral pyloric (LP) motor neuron, remains unaffected by this perturbation. During this period after gastric perturbation, LP neuron and PY neurons thus express opposite burst-to-period relationships in that LP neuron burst duration is independent of the ongoing cycle period, whereas PY neuron burst duration changes with period length. In vitro the same type of gastro- pyloric interaction is observed, indicating that it is not dependent on sensory inputs. Moreover, this interaction is intrinsic to the stomatogastric ganglion itself because the relationship between the two networks persists after suppression of descending inputs to the ganglion. Intracellular recordings reveal that this gastro-pyloric interaction originates from the gastric MG and LG neurons of the gastric network, which inhibit the pyloric pacemaker ensemble. As a consequence, the pyloric PY neurons, which are inhibited by the pyloric dilator (PD) neurons of the pyloric pacemaker group, extend their activity during the time that PD neuron is held silent. Moreover, there is evidence for a pyloro-gastric interaction, apparently rectifying, from the pyloric pacemakers back to the gastric MG/LG neuron group.J Neurophysiol 1998793r1396-408fn Potentials/*physiology92083593Mulloney, B. Hall, W. M.Neurons with histaminelike immunoreactivity in the segmental and stomatogastric nervous systems of the crayfish Pacifastacus leniusculus and the lobster Homarus americanus>8Animal Brain Chemistry Comparative Study Crayfish/*anatomy & histology Esophagus/innervation Ganglia/*chemistry Histamine/*analysis Immunohistochemistry Interneurons/*chemistry Lobsters/*anatomy & histology Neurotransmitters/analysis Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Thorax/innervationWe used a polyclonal antiserum against histamine to map histaminelike immunoreactivity (HLI) in whole mounts of the segmental ganglia and stomatogastric ganglion of crayfish and lobster. Carbodiimide fixation permitted both HRP-conjugated and FITC-conjugated secondary antibodies to be used effectively to visualize HLI in these whole mounts. Two interneurons that send axons through the inferior ventricular nerve (ivn) and the stomatogastric nerve to the stomatogastric ganglion had strong HLI, both in crayfish and in lobster. These ivn interneurons were known from other evidence to be histaminergic. The neuropil of the stomatogastric ganglion in both crayfish and lobster contained brightly labeled terminals of axons that entered the ganglion from the stomatogastric nerve. No neuronal cell bodies in this ganglion had HLI. Each segmental ganglion contained at least one pair of neurons with HLI. Some neurons in the subesophageal ganglion and in each thoracic ganglion labeled very brightly. Axons of projection interneurons with strong HLI occurred in the dorsal lateral tracts of each segmental ganglion, and sent branches to the lateral neurophils and tract neurophils of each ganglion. All the labeled neurons were interneurons; no HLI was observed in peripheral nerves.Cell Tissue Res  1991 266a1i197-207a&%# <$Bartos, M. Nusbaum, M.P. 1997PJIntercircuit control of motor pattern modulation by presynaptic inhibition J Neurosci17 2247-2256>8Bartos, M. Manor, Y. Nadim, F. Marder, E. Nusbaum, M. P.>8Coordination of fast and slow rhythmic neuronal circuitsRLAnimal Crabs Digestive System/*innervation Gastrointestinal Motility/physiology Interneurons/physiology Neural Pathways/physiology Neurons/*physiology *Periodicity Pylorus/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology Synaptic Transmission/physiology Time FactorsInteractions among rhythmically active neuronal circuits that oscillate at different frequencies are important for generating complex behaviors, yet little is known about the underlying cellular mechanisms. We addressed this issue in the crab stomatogastric ganglion (STG), which contains two distinct but interacting circuits. These circuits generate the gastric mill rhythm (cycle period, approximately 10 sec) and the pyloric rhythm (cycle period, approximately 1 sec). When the identified modulatory projection neuron named modulatory commissural neuron 1 (MCN1) is activated, the gastric mill motor pattern is generated by interactions among MCN1 and two STG neurons [the lateral gastric (LG) neuron and interneuron 1]. We show that, during MCN1 stimulation, an identified synapse from the pyloric circuit onto the gastric mill circuit is pivotal for determining the gastric mill cycle period and the gastric-pyloric rhythm coordination. To examine the role of this intercircuit synapse, we replaced it with a computational equivalent via the dynamic-clamp technique. This enabled us to manipulate better the timing and strength of this synapse. We found this synapse to be necessary for production of the normal gastric mill cycle period. The synapse acts, during each LG neuron interburst, to boost rhythmically the influence of the modulatory input from MCN1 to LG and thereby to hasten LG neuron burst onset. The two rhythms become coordinated because LG burst onset occurs with a constant latency after the onset of the triggering pyloric input. These results indicate that intercircuit synapses can enable an oscillatory circuit to control the speed of a slower oscillatory circuit, as well as provide a mechanism for intercircuit coordination.'|vDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074, USA.10414994http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10414994 http://www.jneurosci.org/cgi/content/full/19/15/6650 http://www.jneurosci.org/cgi/content/abstract/19/15/6650 J Neurosci 199919156650-60.ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10879433 >8Bedrov, Y. A. Dick, O. E. Nozdrachev, A. D. Akoev, G. N.b\Method for constructing the boundary of the bursting oscillations region in the neuron modelZSCalcium/physiology Cell Membrane/physiology *Models, Biological Neurons/*physiologyeWe examine the problem of constructing the boundary of bursting oscillations on a parameter plane for the system of equations describing the electrical behaviour of the membrane neuron arising from the interaction of fast oscillations of the cytoplasma membrane potential and slow oscillations of the intracellular calcium concentration. As the boundary point on the parameter plane we consider the values at which the limit cycle of the slow subsystem is tangent to the Hopf bifurcation curve of the fast subsystem. The method suggested for determining the boundary is based on the dissection of the system variables into slow and fast. The strong point of the method is that it requires the integration of the slow subsystem only. An example of the application of the method for the stomatogastric neuron model [Guckenheimer J, Gueron S, Harris-Warrick RM (1993) Philos Trans R Soc Lond B 341: 345-359] is given.'`ZDepartment of Applied Mathematics, Pavlov Institute of Physiology, St. Petersburg, Russia.10879433 Biol Cybern 2000826 493-7.14523066911 2004 JanELong-lasting activation of rhythmic neuronal activity by a novel mechanosensory system in the crustacean stomatogastric nervous system 78-91W~Sensory neurons enable neural circuits to generate behaviors appropriate for the current environmental situation. Here, we characterize the actions of a population (about 60) of bilaterally symmetric bipolar neurons identified within the inner wall of the cardiac gutter, a foregut structure in the crab Cancer borealis. These neurons, called the ventral cardiac neurons (VCNs), project their axons through the crab stomatogastric nervous system to influence neural circuits associated with feeding. Brief pressure application to the cardiac gutter transiently modulated the filtering motor pattern (pyloric rhythm) generated by the pyloric circuit within the stomatogastric ganglion (STG). This modulation included an increased speed of the pyloric rhythm and a concomitant decrease in the activity of the lateral pyloric neuron. Furthermore, 2 min of rhythmic pressure application to the cardiac gutter elicited a chewing motor pattern (gastric mill rhythm) generated by the gastric mill circuit in the STG that persisted for < or =30 min. These sensory actions on the pyloric and gastric mill circuits were mimicked by either ventral cardiac nerve or dorsal posterior esophageal nerve stimulation. VCN actions on the STG circuits required the activation of projection neurons in the commissural ganglia. A subset of the VCN actions on these projection neurons appeared to be direct and cholinergic. We propose that the VCN neurons are mechanoreceptors that are activated when food stored in the foregut applies an outward force, leading to the long-lasting activation of projection neurons required to initiate chewing and modify the filtering of chewed food.'xqDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.4-Beenhakker, M. P. Blitz, D. M. Nusbaum, M. P. 0022-3077 Journal ArticleJ Neurophysiollehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=14523066*) '(( 83137873"Beltz, B. S. Kravitz, E. A.aNHMapping of serotonin-like immunoreactivity in the lobster nervous systemZSAge Factors Animal Central Nervous System/immunology/physiology Fluorescent Antibody Technique Lobsters/*physiology Nervous System/drug effects/immunology/*physiology *Nervous System Physiology Neurons/physiology Peripheral Nerves/physiology Serotonin/immunology/*physiology Support, U.S. Gov't, P.H.S. 5,7-Dihydroxytryptamine/pharmacologynSerotonin exerts a wide range of physiological actions on many different lobster tissues. To begin the examination of the role of serotonin in lobsters at a cellular level, we have used immunohistochemical methods to search for presumptive serotonergic neurons, their central and peripheral projections, and their terminal fields of arborization. Whole mount preparations of the ventral nerve cord and various peripheral nerve structures have been used for these studies. With these tissues, more than 100 cell bodies have been found that show serotonin-like immunoreactivity. Although a few of the cell bodies are located peripherally (near the pericardial organs, a well known crustacean neurohemal organ), the vast majority are located in central ganglia. Every ganglion in the ventral nerve cord contains at least one immunoreactive cell body. The projections of many of the neurons have been traced, and we have constructed a map of the system of serotonin-immunoreactive cell bodies, fibers, and nerve endings. In addition, a dense plexus of nerve endings showing serotonin-like immunoreactivity surrounds each of the thoracic second roots in the vicinity of groups of peripheral neurosecretory neurons. These peripheral nerve plexuses originate from central neurons of the ventral nerve cord. In some cases we have been able to trace processes from particular central cell bodies directly to the peripheral nerve root plexuses; in other cases we have traced ganglionic neuropil regions to these peripheral endings.i J Neurosci 19833p3f585-602s84241568VOBeltz, B. Eisen, J. S. Flamm, R. Harris-Warrick, R. M. Hooper, S. L. Marder, E.(Serotonergic innervation and modulation of the stomatogastric ganglion of three decapod crustaceans (Panulirus interruptus, Homarus americanus and Cancer irroratus) Animal Chromatography, High Pressure Liquid Crabs/*physiology Electrophysiology Female Gastrointestinal System/*innervation Histocytochemistry Immunologic Techniques Lobsters/*physiology Male Motor Activity Serotonin/*analysis/physiology Support, U.S. Gov't, P.H.S.hThe serotonergic innervation of the stomatogastric ganglion (STG) of three decapod crustacean species, Panulirus interruptus, Homarus americanus and Cancer irroratus, was studied. Immunohistochemical techniques were used to study the distribution of serotonin-like staining in regions of the stomatogastric system in the three species. In C. irroratus and H. americanus, but not in P. interruptus, serotonin- like staining was found in fibres in the stomatogastric nerve and in neuropil regions of the STG. High performance liquid chromatography confirmed the presence of serotonin in STG of C. irroratus and H. americanus, but serotonin was not found in STG of P. interruptus. Electrophysiological experiments showed that the pyloric motor output of the STG of all three species was influenced by bath applications of serotonin. The STG of P. interruptus responded to serotonin concentrations as low as 10-9M; however the STG of the other two species did not respond until serotonin concentrations in excess of 10- 6M were applied. We conclude that serotonin may play a hormonal role in the control of the STG of P. interruptus, but is likely to be a neurotransmitter released by inputs to the STG of H. americanus and C. irroratus.o J Exp Biol 1984 109e 35-54s4-Bem, T. Le Feuvre, Y. Simmers, J. Meyrand, P.,hbElectrical coupling can prevent expression of adult-like properties in an embryonic neural circuittnAction Potentials/physiology Animal Biological Clocks/physiology Computer Simulation Electric Conductivity In Vitro Lobsters Membrane Potentials/physiology Models, Neurological Nerve Net/cytology/*embryology/*physiology Neural Inhibition/*physiology Neural Networks (Computer) Neurons/*physiology Periodicity Support, Non-U.S. Gov't Synaptic Transmission/*physiology Electrical coupling is widespread in developing nervous systems and plays a major role in circuit formation and patterning of activity. In most reported cases, such coupling between rhythmogenic neurons tends to synchronize and enhance their oscillatory behavior, thereby producing monophasic rhythmic output. However, in many adult networks, such as those responsible for rhythmic motor behavior, oscillatory neurons are linked by synaptic inhibition to produce rhythmic output with multiple phases. The question then arises whether such networks are still able to generate multiphasic output in the early stage of development when electrical coupling is abundant. A suitable model for addressing this issue is the lobster stomatogastric nervous system (STNS). In the adult animal, the STNS consists of three discrete neural networks that are comprised of oscillatory neurons interconnected by reciprocal inhibition. These networks generate three distinct rhythmic motor patterns with large amplitude neuronal oscillations. By contrast, in the embryo the same neuronal population expresses a single multiphasic rhythm with small-amplitude oscillations. Recent findings have revealed that adult-like network properties are already present early in the embryonic system but are masked by an as yet unknown mechanism. Here we use computer simulation to test whether extensive electrical coupling may be involved in masking adult-like properties in the embryonic STNS. Our basic model consists of three different adult- like STNS networks that are built of relaxation oscillators interconnected by reciprocal synaptic inhibition. Individual model cells generate slow membrane potential oscillations without action potentials. The introduction of widespread electrical coupling between members of these networks dampens oscillation amplitudes and, at moderate coupling strengths, may coordinate neuronal activity into a single rhythm with different phases, which is strongly reminiscent of embryonic STNS output. With a further increase in coupling strength, the system reaches one of two final states depending on the relative contribution of inhibition and inherent oscillatory properties within the networks: either fully synchronized and dampened oscillations, or a complete collapse of activity. Our simulations indicate that, beginning from either of these two states, the emergence of distinct adult networks during maturation may arise from a developmental decrease in electrical coupling that unmasks preexisting adult-like network properties.'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and Centre National de la Recherche Scientifique, Unite Mixte de Recherche 5816, 33405 Talence, France.11784769J Neurophysiol 2002871538-47.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11784769 http://jn.physiology.org/cgi/content/full/87/1/538 http://jn.physiology.org/cgi/content/abstract/87/1/538Benson, J.A. Cooke, I.M. 1984XQDriver potentials and the organization of rhythmic bursting in crustacean ganglia TINS7 85-91P n Potentials/drug effects97461991D=Christie, A. E. Lundquist, C. T. Nassel, D. R. Nusbaum, M. P.`YTwo novel tachykinin-related peptides from the nervous system of the crab Cancer borealisAmino Acid Sequence Animal Crabs/genetics/*metabolism Ganglia, Invertebrate/metabolism Male Molecular Sequence Data Muscle Contraction/drug effects Neuropeptides/genetics/*metabolism/pharmacology Receptors, Tachykinin/antagonists & inhibitors Sequence Homology, Amino Acid Substance P/analogs & derivatives/pharmacology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tachykinins/metabolismztImmunocytochemical and biochemical studies have indicated the presence of many neuroactive substances in the stomatogastric nervous system (STNS) of the crab Cancer borealis. In electrophysiological studies, many of these substances modulate the motor output of neural networks contained within this system. Previous work in the STNS suggested the presence of neuropeptides related to the invertebrate tachykinin- related peptide (TRP) family. Here we isolate and characterize two novel peptides from the C. borealis nervous system that show strong amino acid sequence identity to the invertebrate TRPs. The central nervous systems of 160 crabs were extracted in an acidified solvent, after which four reversed-phase HPLC column systems were used to obtain pure peptides. A cockroach hindgut muscle contraction bioassay and a radioimmunoassay (RIA) employing an antiserum to locustatachykinin I (Lom TK I) were used to monitor all collected fractions. The amino acid sequences of the isolated peptides were determined by Edman degradation. Mass spectrometry and chemical synthesis confirmed the sequences to be APSGFLGMR-NH2 and SGFLGMR-NH2. APSGFLGMR-NH2 is approximately 20-fold more abundant in the crab central nervous system than is SGFLGMR-NH2. We have named these peptides Cancer borealis tachykinin-related peptide Ia and Ib (CabTRP Ia and Ib), respectively. Both peptides are myoactive in the cockroach hindgut muscle contraction bioassay, with CabTRP Ia being approximately 500 times more potent than CabTRP Ib. RIA performed on HPLC-separated C. borealis stomatogastric ganglion (STG) extract revealed that CabTRP Ia is the only detectable TRP-like moiety in this ganglion. Incubation of synthetic CabTRP Ia with the isolated STG excited the pyloric motor pattern. These effects were suppressed by the broad-spectrum tachykinin receptor antagonist Spantide I. Spantide I had no effect on the actions of the unrelated endogenous peptide proctolin in the STG. There was no consistent influence of CabTRP Ib on the pyloric rhythm. Given its amino acid sequence and minimal biological activity in the crab, CabTRP Ib may be a breakdown product of CabTRP Ia. J Exp Biol 1997 200 Pt 172279-94VXVXZ[[\V]`]aaOOb_ccOOOOO_______gghhhhiiijjjjjddjdddddmmmmmsppqsssqqqqqqqttttuwwwwzz{{kkrrrrrkrkk}{zzzrrr|||||||||||||||xy-,x. + 81095905 Bidaut, M.lePharmacological dissection of pyloric network of the lobster stomatogastric ganglion using picrotoxin0*Acetylcholine/physiology Animal Ganglia/anatomy & histology/*drug effects/physiology Glutamates/physiology GABA/physiology In Vitro Lobsters/*physiology Picrotoxin/*pharmacology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/drug effects/physiology Synaptic Transmission/*drug effects 1. Picrotoxin (PTX) (10(-7)-10(-6) M) completely blocked most inhibitory synapses in the pyloric pattern generator of the lobster (Panulirus interruptus) stomatogastric ganglion. The sensitivity of synapses from most classes of identified neurons was examined. Blockade was at least partly reversible with prolonged washing. 2. The synapses from pyloric dilator (PD) neurons were the only inhibitory synapses that picrotoxin failed to block completely. 3. A correlation is derived that brief, fast-rise inhibitory postsynaptic potentials (IPSPs) are picrotoxin sensitive, whereas a slow rounded component of IPSPs from PD neurons is not picrotoxin sensitive. 4. Picrotoxin caused specific changes in the pattern of the motor rhythm produced by the 16-cell pyloric network. This sheds some light on the functional role of particular synapses in the pyloric generator. 5. The endogenously bursting neurons (PD and anterior burster (AB)), which drive the pyloric rhythm, kept a similar burst rate. 6. Under picrotoxin, the pyloric "follower" neurons all moved to later phase relative to the "driver" group. Some normally antagonistic cells, related by reciprocal inhibitor connections, became in-phase. These and other pattern changes could be related to blockade of particular synapses. 7. The pyloric rhythm was still quite recognizable under picrotoxin despite the drastically altered circuitry of the synaptic network. This supports the idea that periodic inhibition from the PD driver neurons plays a primary role in creating the pyloric pattern.J Neurophysiol 1980446 1089-1101w>7Birmingham, J. T. Szuts, Z. B. Abbott, L. F. Marder, E. zsEncoding of muscle movement on two time scales by a sensory neuron that switches between spiking and bursting modescAction Potentials Animal Crabs Digestive System/*innervation In Vitro Movement Muscle, Smooth/*innervation Neurons, Afferent/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Time Factors$The gastropyloric receptor (GPR) neurons of the stomatogastric nervous system of the crab Cancer borealis are muscle stretch receptors that can fire in either a spiking or a bursting mode of operation. Our goal is to understand what features of muscle stretch are encoded by these two modes of activity. To this end, we characterized the responses of the GPR neurons in both states to sustained and rapidly varying imposed stretches. The firing rates of spiking GPR neurons in response to rapidly varying stretches were directly related to stretch amplitude. For persistent stretches, spiking-mode firing rates showed marked adaptation indicating a more complex relationship. Interspike intervals of action potentials fired by GPR neurons in the spiking mode were used to construct an accurate estimate of the time-dependent amplitude of stretches in the frequency range of the gastric mill rhythm (0.05-0.2 Hz). Spike trains arising from faster stretches (similar to those of the pyloric rhythm) were decoded using a linear filter to construct an estimate of stretch amplitude. GPR neurons firing in the bursting mode were relatively unaffected by rapidly varying stretches. However, the burst rate was related to the amplitude of long, sustained stretches, and very slowly varying stretches could be reconstructed from burst intervals. In conclusion, the existence of spiking and bursting modes allows a single neuron to encode both rapidly and slowly varying stimuli and thus to report cycle-by-cycle muscle movements as well as average levels of muscle tension.'haVolen Center and Biology Department, Brandeis University, Waltham, Massachusetts 02454-9110, USA.10561445http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10561445 http://www.jn.org/cgi/content/full/82/5/2786 http://www.jn.org/cgi/content/abstract/82/5/2786J Neurophysiol 19998252786-97.ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11341585rBirmingham, J. T. <5Increasing sensor flexibility through neuromodulationEBoth biological and man-made motor control networks require input from sensors to allow for modification of the motor program. Real sensory neurons are more flexible than typical robotic sensors because they are dynamic rather than static. The membrane properties of neurons and hence their excitability can be modified by the presence of neuromodulatory substances. In the case of a sensory neuron, this can change, in a functionally significant way, the code used to describe a stimulus. For instance, extension of the neuron's dynamic range or modification of its filtering characteristics can result. This flexibility has an apparent cost. The code used may be situation- dependent and hence difficult to interpret. To address this issue and to understand how neuromodulation is used effectively in a motor control network, I am studying the GPR2 stretch receptor in the crustacean stomatogastric nervous system. Several different neuromodulatory substances can modify its encoding properties. Comparisons of physiological and anatomical evidence suggest that neuromodulation can be effected both by GPR2 itself and by other neurons in the network. These results suggest that the analog of neuromodulation might be useful for improving sensor performance in an artificial motor control system.'haVolen Center and Biology Department, Brandeis University, Waltham, Massachusetts 02454-9110, USA.a11341585 Biol BullG 2001 200t2 206-10. 12944539 2003 Aug 27}Differential and history-dependent modulation of a stretch receptor in the stomatogastric system of the crab, Cancer borealisNeuromodulators can modify the magnitude and kinetics of the response of a sensory neuron to a stimulus. Six neuroactive substances modified the activity of the gastropyloric receptor 2 (GPR2) neuron of the stomatogastric nervous system (STNS) of the crab Cancer borealis during muscle stretch. Stretches were applied to the gastric mill 9 (gm9) and the cardio-pyloric valve 3a (cpv3a) muscles. SDRNFLRFamide and dopamine had excitatory effects on GPR2. Serotonin, GABA, and the peptide allatostatin-3 (AST) decreased GPR2 firing during stretch. Moreover, SDRNFLRFamide and TNRNFLRFamide increased the unstimulated spontaneous firing rate, while GABA and AST decreased it. The actions of GABA and AST were amplitude and history-dependent. In fully recovered preparations, AST and GABA decreased the response to small amplitude stretches proportionally more than to those evoked by large amplitude stretches. For large amplitude stretches, the effects of AST and GABA were more pronounced as the number of recent stretches increased. The modulators that affected the stretch-induced GPR2 firing rate were also tested when the neuron was operating in a bursting mode of activity. Application of SDRNFLRFamide increased the bursting frequency transiently, while high concentrations of serotonin, AST, and GABA abolished bursting altogether. Together these data demonstrate that the effects of neuromodulators depend upon the previous activity and current state of the sensory neuron.'JDDepartment of Physics, Santa Clara University, Santa Clara, CA, USA.RLBirmingham, J. T. Billimoria, C. P. DeKlotz, T. R. Stewart, R. A. Marder, E."0 0022-3077 Journal articlecJ Neurophysiollehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12944539a/ 10 J95301752<6Blitz, D. M. Christie, A. E. Marder, E. Nusbaum, M. P.|vDistribution and effects of tachykinin-like peptides in the stomatogastric nervous system of the crab, Cancer borealisAmino Acid Sequence Animal Crabs/*physiology Electrophysiology Ganglia, Invertebrate/drug effects/*metabolism/physiology Immunohistochemistry Insect Hormones/metabolism/pharmacology Molecular Sequence Data Periodicity Pylorus/drug effects/physiology Stomach/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Tachykinins/*metabolism/pharmacology/*physiology Tissue DistributionnThe rhythmically active pyloric and gastric mill motor patterns in the stomatogastric ganglion of the crab, Cancer borealis, are influenced by modulatory projection neurons whose somata are located primarily in the other ganglia of the stomatogastric nervous system. One of these projection neurons exhibits substance P-like immunolabeling. However, bath application of substance P does not influence these motor patterns. To determine whether a different peptide is responsible for the substance P-like immunolabeling, we studied the presence and physiological effects of the locustatachykinins and the leucokinins, two families of tachykinin-like peptides originally identified in insect nervous systems. Locustatachykinin-like immunolabeling has the same distribution in the stomatogastric nervous system as substance P- like immunolabeling and colocalizes with it in the majority of immunopositive structures. Preincubation of locustatachykinin antibody with substance P, and preincubation of substance P antibody with locustatachykinin, blocks subsequent immunolabeling in the stomatogastric nervous system. In contrast, we found no leucokinin-like immunolabeling in this system. Bath application to the stomatogastric ganglion of individual locustatachykinins or leucokinins excited the pyloric rhythm in a state-dependent manner. Each peptide family had distinct effects on the pyloric rhythm. Thus, both of these tachykinin- like peptide families are likely related to native neuropeptides that influence the pyloric rhythm. Furthermore, a member of the locustatachykinin family is likely to be the source of the previously identified substance P-like immunoreactivity in the stomatogastric nervous system. J Comp Neurol 1995 3542 282-94nghttp://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.jneurosci.org/cgi/content/full/17/13/496597331009"Blitz, D. M. Nusbaum, M. P.B;Motor pattern selection via inhibition of parallel pathwaysf|vAnimal Crabs Esophagus/innervation Ganglia, Invertebrate/*physiology Motor Activity/*physiology Nerve Net/physiology *Neural Inhibition Neural Pathways/physiology Neurons/physiology Neurotransmitters/physiology Oligopeptides/physiology *Periodicity Stomach/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synaptic TransmissionMotor pattern selection from a multifunctional neural network often results from direct synaptic and modulatory actions of different projection neurons onto neural network components. Less well documented is the presence and function of interactions among distinct projection neurons innervating the same network. In the stomatogastric nervous system of the crab Cancer borealis, several distinct projection neurons that influence the pyloric and gastric mill rhythms have been studied. These rhythms are generated by overlapping subsets of identified neurons in the stomatogastric ganglion (STG). One of these identified projection neurons is the modulatory proctolin neuron (MPN). We showed previously that MPN stimulation excites the pyloric rhythm by its excitatory actions on STG neurons. In contrast to its excitatory actions on the pyloric rhythm, we have now found that MPN inhibits the gastric mill rhythm. This inhibition does not occur within the STG, but instead results from MPN-mediated inhibition of two previously identified projection neurons within the commissural ganglia. These projection neurons innervate the STG and, via their actions on STG neurons, they elicit the gastric mill rhythm as well as modify the pyloric rhythm in a manner distinct from MPN. By inhibiting these projection neurons, MPN removes excitatory drive to gastric mill neurons and elicits an MPN-specific pyloric rhythm. Motor pattern selection by MPN therefore results from both a direct modulation of STG network activity and an inhibition of competing pathways. J Neurosci 199717134965-75ZSBlitz, D. M. Christie, A. E. Coleman, M. J. Norris, B. J. Marder, E. Nusbaum, M. P.hbDifferent proctolin neurons elicit distinct motor patterns from a multifunctional neuronal networkAnimal Crabs Electrophysiology Ganglia, Invertebrate/anatomy & histology/*cytology/physiology Immunohistochemistry In Vitro Motor Activity Motor Neurons/metabolism/*physiology Nerve Net/anatomy & histology/metabolism/*physiology Neural Pathways Neurotransmitters/metabolism/physiology Oligopeptides/metabolism/*physiology Periodicity Stomach/innervation/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/chemistry/physiology *Synaptic TransmissionDistinct motor patterns are selected from a multifunctional neuronal network by activation of different modulatory projection neurons. Subsets of these projection neurons can contain the same neuromodulator(s), yet little is known about the relative influence of such neurons on network activity. We have addressed this issue in the stomatogastric nervous system of the crab Cancer borealis. Within this system, there is a neuronal network in the stomatogastric ganglion (STG) that produces many versions of the pyloric and gastric mill rhythms. These different rhythms result from activation of different projection neurons that innervate the STG from neighboring ganglia and modulate STG network activity. Three pairs of these projection neurons contain the neuropeptide proctolin. These include the previously identified modulatory proctolin neuron and modulatory commissural neuron 1 (MCN1) and the newly identified modulatory commissural neuron 7 (MCN7). We document here that each of these neurons contains a unique complement of cotransmitters and that each of these neurons elicits a distinct version of the pyloric motor pattern. Moreover, only one of them (MCN1) also elicits a gastric mill rhythm. The MCN7-elicited pyloric rhythm includes a pivotal switch by one STG network neuron from playing a minor to a major role in motor pattern generation. Therefore, modulatory neurons that share a peptide transmitter can elicit distinct motor patterns from a common target network.'|vDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074, USA.10377354http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10377354 http://www.jneurosci.org/cgi/content/full/19/13/5449 http://www.jneurosci.org/cgi/content/abstract/19/13/5449 J Neurosci 199919135449-63.152822772430 2004 Jul 28\VMechanosensory activation of a motor circuit by coactivation of two projection neurons6741-50nIndividual neuronal circuits can generate multiple activity patterns because of the influence of different projection neurons. However, in most systems it has been difficult to identify and assess the relative contribution of all upstream neurons responsible for the activation of any single activity pattern by a behaviorally relevant stimulus. To elucidate this issue, we used the stomatogastric nervous system (STNS) of the crab. The STNS includes the gastric mill (chewing) motor circuit in the stomatogastric ganglion (STG) and no more than 20 projection neurons that innervate the STG. We previously identified at least some (four) of the projection neurons that are activated directly by the ventral cardiac neuron (VCN) system, a population of mechanosensory neurons that activates the gastric mill circuit. Here we show that two of these projection neurons, the previously identified modulatory commissural neuron 1 (MCN1) and commissural projection neuron 2 (CPN2), are necessary and likely sufficient for the initiation/maintenance of the VCN-elicited gastric mill rhythm. Selective inactivation of either MCN1 or CPN2 still enabled a VCN-elicited gastric mill rhythm. However, because MCN1 and CPN2 have different actions on gastric mill neurons, these manipulations resulted in rhythms distinct from each other and from that occurring in the intact system. After removal of both MCN1 and CPN2, VCN stimulation failed to activate the gastric mill rhythm. Selective conjoint stimulation of MCN1 and CPN2, approximating their VCN-elicited activity patterns and firing frequencies, elicited a VCN-like gastric mill rhythm. Thus the VCN mechanosensory system elicits the gastric mill rhythm via its activation of a subset of the relevant projection neurons.M'|vDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074, USA.& Beenhakker, M. P. Nusbaum, M. P. 1529-2401 Journal Article J Neuroscilehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15282277ajb` 95017000B 10(-6) M) were used, and neither Proct. nor Proct. (10(-4) M) influenced the pyloric rhythm. Our results indicate that proctolin is enzymatically degraded and thereby biologically inactivated in the crab nervous system, primarily by extracellularly located aminopeptidase activity. J Neurosci 199414106205-16t95054373$Coleman, M. J. Nusbaum, M. P.HAFunctional consequences of compartmentalization of synaptic inputnAnimal Crabs Dendrites/ultrastructure Electrophysiology Ganglia, Invertebrate/physiology/ultrastructure Male Neural Inhibition Presynaptic Terminals/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/*physiology`ZIntra-axonal recordings of stomatogastric nerve axon 1 (SNAX1) indicate that there are synaptic inputs onto the SNAX1 terminals in the stomatogastric ganglion (STG) of the crab Cancer borealis (Nusbaum et al., 1992b). To determine whether this synaptic input only influenced SNAX1 activity within the STG, we identified the SNAX1 soma in the commissural ganglion (CoG). We found that this neuron has a neuropilar arborization in the CoG and also receives synaptic inputs in this ganglion. Based on its soma location, we have renamed this neuron modulatory commissural neuron 1 (MCN1). While intracellular stimulation of MCN1soma and MCN1SNAX has the same excitatory effects on the STG motor patterns, MCN1 receives distinct synaptic inputs in the STG and CoG. Moreover, the synaptic input that MCN1 receives within the STG compartmentalizes its activity. Specifically, the lateral gastric (LG) neuron synaptically inhibits MCN1SNAX-initiated activity within the STG (Nusbaum et al., 1992b), and while LG did not inhibit MCN1soma- initiated activity in the CoG, it did inhibit these MCN1 impulses when they arrived in the STG. As a result, during MCN1soma-elicited gastric mill rhythms, MCN1soma is continually active in the CoG but its effects are rhythmically inhibited in the STG by LG neuron impulse bursts. One functional consequence of this local control of MCN1 within the STG is that the LG neuron thereby controls the timing of the impulse bursts in other gastric mill neurons. Thus, local synaptic input can functionally compartmentalize the activity of a neuron with arbors in distinct regions of the nervous system. J Neurosci 19941411 Pt 1p6544-52s960850310)Coleman, M. J. Meyrand, P. Nusbaum, M. P.6\VA switch between two modes of synaptic transmission mediated by presynaptic inhibition<5Acetic Acids/pharmacology Action Potentials Animal Crabs Ganglia, Invertebrate/physiology Male Nerve Net/physiology Neural Inhibition/*physiology Presynaptic Terminals/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synaptic Transmission/drug effects/*physiologya\UPresynaptic inhibition reduces chemical synaptic transmission in the central nervous system between pairs of neurons, but its role(s) in shaping the multisynaptic interactions underlying neural network activity are not well studied. We therefore used the crustacean stomatogastric nervous system to study how presynaptic inhibition of the identified projection neuron, modulatory commissural neuron 1 (MCN1), influences the MCN1 synaptic effects on the gastric mill neural network. Tonic MCN1 discharge excites gastric mill network neurons and activates the gastric mill rhythm. One network neuron, the lateral gastric (LG) neuron, presynaptically inhibits MCN1 and is electrically coupled to its terminals. We show here that this presynaptic inhibition selectively reduces or eliminates transmitter-mediated excitation from MCN1 without reducing its electrically mediated excitatory effects, thereby switching the network neurons excited by MCN1. By switching the type of synaptic output from MCN1 and, hence, the activated network neurons, this presynaptic inhibition is pivotal to motor pattern generation.  Nature 1995 378  6556 502-5r>=<j;:9892235704<5Buchholtz, F. Golowasch, J. Epstein, I. R. Marder, E.iHBMathematical model of an identified stomatogastric ganglion neuronAction Potentials/drug effects Animal Crabs/*physiology Electrophysiology Ganglia/cytology/*physiology Ion Channels/drug effects/physiology Models, Biological Neurons/drug effects/*physiology Neurotransmitters/pharmacology Oligopeptides/pharmacology Pylorus/*innervation Sodium Channels/drug effects/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Tetrodotoxin/pharmacologyZS1. The ionic currents in the lateral pyloric (LP) cell of the stomatogastric ganglion (STG) described in the preceding paper of the rock crab Cancer borealis were fit with a set of differential equations that describe their voltage, time, and Ca2+ dependence. The voltage- dependent currents modeled are a delayed rectifier-like current, id; a Ca(2+)-activated outward current, io(Ca); a transient A-like current, iA; a Ca2+ current, iCa; an inwardly rectifying current, ih; and a fast tetrodotoxin (TTX)-sensitive Na+ current, iNa. 2. A single-compartment, isopotential model of the LP cell was constructed from the six voltage- dependent currents, a voltage-independent leak current il, a Ca2+ buffering system, and the membrane capacitance. 3. The behavior of the model LP neuron was compared with that of the biological neuron by simulating physiological experiments carried out in both voltage-clamp and current-clamp modes. The model and biological neurons show similar action-potential shapes, durations, steady-state current-voltage (I-V) curves, and respond to injected current in a comparable way.cJ Neurophysiol 1992672L 332-40ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10788671)<6Cabirol-Pol, M. J. Mizrahi, A. Simmers, J. Meyrand, P.Combining laser scanning confocal microscopy and electron microscopy to determine sites of synaptic contact between two identified neurons,%Animal Female Fluorescent Dyes Ganglia, Invertebrate/cytology Horseradish Peroxidase Immunohistochemistry Isoquinolines Lobsters Male Microscopy, Confocal/*methods Microscopy, Immunoelectron/*methods Microtomy Neurons/*ultrastructure Rhodamines Support, Non-U.S. Gov't Synapses/*ultrastructureHere we report a double labelling method for correlative confocal and electron microscopy (EM) which allows selective characterisation of structural relationships between two single identified neurons in the same preparation. Using the lobster stomatogastric nervous system, we labelled pairs of identified, synaptically-connected neurons by intracellular injection of Lucifer Yellow (LY) in one neuron and a mixture of Rhodamine (Rdh) and Horseradish Peroxidase (HRP) in its partner. First, whole-mounts of LY- and Rdh-stained neurons were visualized using laser scanning confocal microscopy (LSCM) in order to isolate neuropilar regions of possible synaptic contact. Second, after conventional treatment for electron microscopy (LY was revealed with immunogold and HRP with DAB), areas of close appositions were viewed in EM. This technique allowed us to determine all the regions of close contact between two cells, and then to use electron microscopy to determine the presence or absence of synaptic contact within each of these restricted areas. These techniques enabled us to show that there were few areas of apposition and that only an extremely small proportion of these areas was in fact regions of synaptic contact between the two labelled neurons.'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and CNRS UMR 5816, Avenue des Facultes, 33405, Talence, France.10788671J Neurosci Methods 2000972175-81. Caine, E.A. 1975^WFeeding and masticatory structures of six species of the crayfish (Decapoda, Astacidae)Forma et Functio8 49-66Calabrese, R. L. 1991The center cannot hold Curr BiolE1t3w185-187m'xqDepartment of Biology Emory University 1510 Clifton Road, Atlanta, Georgia 30322, USA. rcalabre@biology.emory.edue991424418062 1998 DecZTCellular, synaptic, network, and modulatory mechanisms involved in rhythm generation 710-7iThe membrane properties and the synaptic interactions of individual neurons, as well as the interactions between neuronal networks, all contribute to the formation of the complex patterns of activity that underlie rhythmic motor patterns and slow-wave sleep rhythms. These properties and interactions are potential points of modulation for further refining network output. Recent work illustrates the range of these properties and interactions and suggests how they may be modulated.r'zsDepartment of Biology, Emory University, 1510 Clifton Road, Atlanta, Georgia 30322, USA. rcalabre@biology.emory.edueCalabrese, R. L.@:99116055 0959-4388 Journal Article Review Review, TutorialCurr Opin NeurobioltAnimal Nerve Net/*physiology Neurons/*physiology Neurotransmitters/*physiology *Periodicity Support, U.S. Gov't, P.H.S. Synapses/*physiologyjdhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9914244Calabrese, R. L."Taking the lead from a modelAnimal Crabs/*physiology Ganglia, Invertebrate/*physiology Gastrointestinal Motility/*physiology Gastrointestinal System/*innervation *Models, Neurological Motor Neurons/*physiology Muscle Contraction Muscle, Smooth/innervation :4It is rare these days that theory leads experiment in the biological sciences, but it still happens. A recent study has experimentally confirmed the predictions of a model aimed at explaining how neural networks interact to produce the coordinated patterns of motor activity necessary for effective behavior.'xqDepartment of Biology Emory University 1510 Clifton Road, Atlanta, Georgia 30322, USA. rcalabre@biology.emory.edu10508603 Curr Biol 1999918R680-3.{http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10508603 http://www.biomednet.com/article/bb9r10871864592+Callaway, J. C. Masinovsky, B. Graubard, K.f`Co-localization of SCPB-like and FMRFamide-like immunoreactivities in crustacean nervous systemsAntibodies, Monoclonal/diagnostic use Crabs/*analysis Nervous System/analysis Neuropeptides/*analysis Species Specificity Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.sLFA monoclonal antibody to the molluscan small cardioactive peptide SCPB and a polyclonal antibody to FMRFamide were used to localize antigens in the stomatogastric nervous system and brain of two species of Cancer. Both antibodies labeled cell bodies, axons, and neuropilar processes in the brain and in the stomatogastric nervous system. All of the SCPB immunoreactive neurons were co-labeled with antibody to FMRFamide. However, antibody to FMRFamide labeled additional neurons of the commissural ganglion and the brain that were not immunoreactive to the monoclonal SCPB antibody. Brain Resr 1987 405o2"295-304 DCA@B?477096046$Calvin, W. H. Hartline, D. K.arkRetrograde invasion of lobster stretch receptor somata in control of firing rate and extra spike patterningAnimal Electric Stimulation Electrophysiology Lobsters/*physiology Mechanoreceptors/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.e1. Extra spikes may be interleaved in the otherwise rhythmic discharge pattern of the lobster stretch receptor neuron, about 2 ms after an expected spike. A constant input to the neuron is maintained by injecting current intrasomatically. The axon recovers its excitability while the retrograde invasion of the soma and dendrites is still in progress, which provide electrotonic currents to reexcite the axon. 2. While extra spikes in the axon often arise from a prolonged somatic (dendritic?) depolarization, they may also arise from a delayed retrograde invasion of the soma. 3. Failure of retrograde invasion may cause a sudden jump in the rate of rhythmic discharge, demonstrating the role of the soma-dendritic afterhyperpolarization in the regulation of rhythmic firing rate. 4. The history of repetitive firing is often important. Because extra spikes often first appear during a decline in firing rate, turning on and then off, an additional current may sometimes activate the extra spike mode, thus doubling the resting firing rate in a metastable manner. Another mestastable state is associated with failure of retrograde invasion. 5. Extra spikes augment the high end of the frequency-current curve in some receptor neurons; in other cases, the extra spikes are seen only at low rhythmic firing rates, dropping out as current reaches intermediate values to create a paradoxical negative-sensitivity region (decline in total spikes per second with increasing current). 6. The results suggest that both the extent and the speed of active retrograde invasion of the soma and dendrites are likely candidates for pathophysiological mechanisms, since they may control whether extra spikes are generated.J Neurophysiol 1977401u 106-184-Cardi, P. Nagy, F. Cazaletz, J.R. Moulins, M. 1990Multimodal distribution and discontinuous variation in period of interacting oscillators in the crustacean stomatogastric nervous systemJ Comp Physiol 167 23-41A Cardi, P. 1991Controle modulateur rhythmique d'un reseau du systeme nerveux stomatogastrique des crustaces: Etude anatomique, electrophysiologique et pharmacologique Bordeaux, France University of Bordeaux Ph.D.A95016938Cardi, P. Nagy, F.A rhythmic modulatory gating system in the stomatogastric nervous system of Homarus gammarus. III. Rhythmic control of the pyloric CPGd]Animal Electric Stimulation Female Ganglia, Invertebrate/*physiology Gastric Emptying/physiology Laterality/physiology Lobsters/*physiology Male Membrane Potentials/physiology Mouth/*innervation Nerve Net/*physiology Neural Inhibition/*physiology Neurons/physiology Pyloric Antrum/*physiology Support, Non-U.S. Gov't Synaptic Transmission/physiologyo1. Two modulatory neurons, P and commissural pyloric (CP), known to be involved in the long-term maintenance of pyloric central pattern generator operation in the rock lobster Homarus gammarus, are members of the commissural pyloric oscillator (CPO), a higher-order oscillator influencing the pyloric network. 2. The CP neuron was endogenously oscillating in approximately 30% of the preparations in which its cell body was impaled. Rhythmic inhibitory feedback from the pyloric pacemaker anterior burster (AB) neuron stabilized the CP neuron's endogenous rhythm. 3. The organization of the CPO is described. Follower commissural neurons, the F cells, and the CP neuron receive a common excitatory postsynaptic potential from another commissural neuron, the large exciter (LE). When in oscillatory state, CP in turn excites the LE neuron. This positive feedback may maintain long episodes of CP oscillations. 4. The pyloric pacemaker neurons follow the CPO rhythm with variable coordination modes (i.e., 1:1, 1:2) and switch among these modes when their membrane potential is modified. The CPO inputs strongly constrain the pyloric period, which as a result may adopt only a few discrete values. This effect is based on mechanisms of entrainment between the CPO and the pyloric oscillator. 5. Pyloric constrictor neurons show differential sensitivity from the pyloric pacemaker neurons with respect to the CPO inputs. Consequently, their bursting period can be a shorter harmonic of the bursting period of the pyloric pacemakers neurons. 6. The CPO neurons seem to be the first example of modulatory gating neurons that also give timing cues to a rhythmic pattern generating network.J Neurophysiol 19947162503-16"Carlton, C.E. Schmitz, E.H.a 1989PAnatomy of the extrinsic gut musculature of Gammarus minus (Crustacea Amphipoda),: J Morphol 200r 87-92d95370934 Casasnovas, B. Meyrand, P.ZSFunctional differentiation of adult neural circuits from a single embryonic networkAnimal Digestive System/embryology/innervation *Fetal Development Lobsters/*embryology Motor Activity/physiology Nerve Net/*embryology Nervous System/*embryology Neural Pathways/embryology Neuromuscular Junction/embryology Periodicity Support, Non-U.S. Gov'tThe stomatogastric nervous system (STNS) of adult lobsters and crabs generates a number of different rhythmic motor patterns which control different regional movements of the foregut. Since these output patterns are generated by discrete neural networks that, in the adult, are well characterized in terms of synaptic and cellular properties, this system constitutes an ideal model for exploring the mechanisms underlying the ontogeny of neural network organization. The foregut and its rhythmic motor patterns were studied in in vitro STNS nerve-muscle preparations of the embryo and different larval stages of the lobster Homarus gammarus. The development of Homarus comprises a long embryonic stage in ovo followed by three pelagic larval stages prior to the onset of benthic life. During these stages the foregut itself develops slowly from a simple ectodermal invagination that occurs in the embryo. During successive larval stages it progressively acquires all the specialized structures and shape of the adult foregut. In contrast, the STNS is morphologically recognizable at early embryonic stages. In all recorded stages the STNS spontaneously expresses rhythmic motor activity. During development, this activity is progressively restructured, beginning with a single rhythmic motor pattern in the embryo where all the stomodeal muscles are strongly coordinated. In subsequent stages, however, this single pattern is progressively subdivided to give rise eventually to the three discrete rhythmic motor patterns characteristic of the adult STNS. Our data suggest that rather than a dismantling of redundant embryonic and larval neural networks, the different adult networks emerge as a progressive partitioning of discrete circuits from a single embryonic network. J Neurosci 19951585703-18IH .G4FE87310635:3Cazalets, J. R. Cournil, I. Geffard, M. Moulins, M.nhbSuppression of oscillatory activity in crustacean pyloric neurons: implication of GABAergic inputsAnimal Electric Stimulation Electrophysiology GABA/analysis Histocytochemistry Lobsters Muscimol/metabolism Neurons/*physiology Pyloric Antrum/*innervation Support, Non-U.S. Gov't Tetrodotoxin/pharmacology Generation of rhythmic pyloric motor output in the crustacean stomatogastric ganglion results from synaptic connections and cellular properties of a 14-cell network of pyloric neurons. These cellular properties are under the influences of modulatory inputs, which act, for the most part, in an activating mode, i.e., they enhance the bursting properties of the pyloric neurons and/or their ability to express their regenerative properties. Here we attempt to demonstrate that the pyloric motor output is also under the control of suppressive afferent inputs that are able to stop the pyloric rhythm in a long- lasting manner. Immunohistochemistry, using GABA antibodies, indicates that GABAergic-like fibers are present in both the stomatogastric ganglion and its afferent nerve. Bath-applied GABA suppresses spontaneous pyloric rhythmic activity. This is due to an inability of the pyloric pacemakers to express their bursting properties. The suppressive effect of GABA is blocked by picrotoxin and mimicked by muscimol. Isolating the pyloric neurons from all descending spiking influences with tetrodotoxin demonstrates that exogenously applied GABA acts directly on the pyloric neurons. To confirm the existence of a physiological suppressive system for the pyloric motor pattern, we show that the stimulation of an afferent nerve, known to contain GABA-like fibers, also causes the cessation of rhythmic activity and the inability of the pyloric neurons to express their bursting properties.m J Neurosci 19877u9o2884-93i88123180*$Cazalets, J. R. Nagy, F. Moulins, M.rkSuppressive control of a rhythmic central pattern generator by an identified modulatory neuron in crustaceafAction Potentials Animal *Biological Clocks Ganglia/cytology/physiology In Vitro Lobsters/*physiology Motor Neurons/*physiology Pylorus/innervation/physiology Support, Non-U.S. Gov't The activity of the 14 neuron network which organizes the pyloric motor rhythm in the stomatogastric ganglion of the lobster, Homarus gammarus, is controlled by neuromodulatory inputs which have been described as having mainly 'permissive' effects. By contrast, here we identify a neuron, the pyloric suppressor (PS) neuron which exerts a 'suppressive' effect on the pyloric activity. We show that PS neuron discharge can terminate in a long-lasting manner, spontaneous pyloric rhythmic activity. Its effect results from a direct suppression of the endogenous ability of the pyloric pacemaker neurons to produce rhythmic bursts of action potentials. Thus the output of the pyloric neuronal network appears to be finely tuned by neuromodulatory influences having opposite effects.n Neurosci Lettc 1987813r 267-7290155415*$Cazalets, J. R. Nagy, F. Moulins, M.Suppressive control of the crustacean pyloric network by a pair of identified interneurons. II. Modulation of neuronal propertieswAnimal Brain/cytology/*physiology Digestive System/*innervation Electrophysiology Interneurons/*physiology Lobsters/*physiology Nerve Net/cytology/*physiology Nervous System/*physiology *Nervous System Physiology Pylorus Support, Non-U.S. Gov't Time Factorsu4.In the lobster Homarus, the 2 identified PS neurons have a strong suppressive modulatory effect on the activity of the pyloric network in the STG (Cazalets et al., 1990). In the present paper, we consider the effects of PS on individual pyloric neurons isolated from their partners in the network by cell photoinactivation and synaptic blockade. Three types of PS action are described: (1) a transient, EPSP- mediated depolarization of the PD, VD, and AB neurons; (2) a long- lasting hyperpolarization concomitant with a loss of oscillatory properties in the PD and LP neurons; (3) a long-lasting depolarization without modification of oscillatory properties in the PY and IC neurons. The various effects of PS on isolated pyloric cells were consistent with the overall effects of PS on the intact pyloric network. J Neurosci 1990102 458-6890155414*$Cazalets, J. R. Nagy, F. Moulins, M.~Suppressive control of the crustacean pyloric network by a pair of identified interneurons. I. Modulation of the motor pattern,&Animal Brain/cytology/*physiology Digestive System/*innervation Electrophysiology Ganglia/physiology Interneurons/*physiology Lobsters/*physiology Motor Activity/*physiology Nerve Net/*physiology Nervous System/*physiology *Nervous System Physiology Pylorus Support, Non-U.S. Gov't Time FactorsA pair of identified neuromodulatory neurons, the pyloric suppressor (PS) neurons, can individually and strongly modify the activity of the pyloric network in the stomatogastric nervous system of the lobster Homarus gammarus. The PS neurons are identified by the location of their somata in the inferior ventricular nerve, their axonal projections, and their effects on pyloric network activity in vitro. Discharge of a PS neuron evokes large EPSPs in the pyloric dilator (PD) neurons and a long-lasting cessation of rhythmic activity in the neurons that control movements of the pyloric filter: PD, lateral pyloric (LP), and pyloric (PY). This cessation of rhythmic activity can outlast by several 10s of seconds a brief discharge of PS lasting only a few seconds. The different neurons of the pyloric filter do not exhibit the same sensitivity to the suppressive effects of PS, with the LP neuron being the most sensitive. Tonic discharge in PS induces graded alterations in the pyloric pattern, depending on its firing frequency. At low (less than 5 Hz) discharge frequencies, PS provokes changes in phase relationships and duration of bursting in pyloric neurons. A slight increase in PS frequency suppresses the rhythmic activity of some pyloric neurons, resulting in a switch from a triphasic to a biphasic pattern. At higher (greater than 10 Hz) PS firing frequencies, rhythmic activity in all the pyloric neurons, including the pacemakers (PD, anterior burster), is abolished, except in cells (ventricular dilator, inferior cardiac) controlling the pyloric valve. We conclude that a central pattern generator is not only subject to activating modulatory control, but may also be the target of suppressive inputs that are themselves able to provoke functional reconfigurations of the network.  J Neurosci 1990102t 448-57*#Chabaud, F. Friedi, M. Reichert, H. 1991JDNeuronal development of the crustacean stomatogastric nervous system Penzlin, H. Elsner, N.(!Synapse, Transmission, Modulatione Thieme Verlag 495g6532 "Blitz, D. M. Nusbaum, M. P. NGDistinct functions for cotransmitters mediating motor pattern selectionHAAnimal Crabs/*physiology GABA/pharmacology Ganglia, Invertebrate/drug effects/physiology Motor Neurons/drug effects/physiology Nerve Net/drug effects/physiology Neurotransmitters/physiology Oligopeptides/physiology Pyloric Antrum/innervation Stomach/innervation Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Motor patterns are selected from multifunctional networks by selective activation of different projection neurons, many of which contain multiple transmitters. Little is known about how any individual projection neuron uses its cotransmitters to select a motor pattern. We address this issue by using the stomatogastric ganglion (STG) of the crab Cancer borealis, which contains a neuronal network that generates multiple versions of the pyloric and gastric mill motor patterns. The functional flexibility of this network results mainly from modulatory inputs it receives from projection neurons that originate in neighboring ganglia. We demonstrated previously that the STG motor pattern selected by activation of the modulatory proctolin neuron (MPN) results from direct MPN modulation of the pyloric rhythm and indirect MPN inhibition of the gastric mill rhythm. The latter action results from MPN inhibition of projection neurons that excite the gastric mill rhythm. These projection neurons are modulatory commissural neuron 1 (MCN1) and commissural projection neuron 2 (CPN2). MPN excitation of the pyloric rhythm is mimicked by bath application of proctolin, its peptide transmitter. Here, we show that MPN uses only its small molecule transmitter, GABA, to inhibit MCN1 and CPN2 within their ganglion of origin. We also demonstrate that MPN has no proctolin- mediated influence on MCN1 or CPN2, although exogenously applied proctolin directly excites these neurons. Thus, motor pattern selection occurs during MPN activation via proctolin actions on the STG network and GABA-mediated actions on projection neurons in the commissural ganglia, demonstrating a spatial and functional segregation of cotransmitter actions.'|vDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074, USA.10436035http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10436035 http://www.jneurosci.org/cgi/content/full/19/16/6774 http://www.jneurosci.org/cgi/content/abstract/19/16/6774 J Neurosci 199919166774-83.156019442450 2004 Dec 15\UDifferent sensory systems share projection neurons but elicit distinct motor patterns11381-90Considerable research has focused on issues pertaining to sensorimotor integration, but in most systems precise information remains unavailable regarding the specific pathways by which different sensory systems regulate any single central pattern-generating circuit. We address this issue by determining how two muscle stretch-sensitive neurons, the gastropyloric receptor neurons (GPRs), influence identified projection neurons that regulate the gastric mill circuit in the stomatogastric nervous system of the crab and then comparing these actions with those of the ventral cardiac neuron (VCN) mechanosensory system. Here, we show that the GPR neurons activate the gastric mill rhythm in the stomatogastric ganglion (STG) via their excitation of two identified projection neurons, modulatory commissural neuron 1 (MCN1) and commissural projection neuron 2 (CPN2), in the commissural ganglion. Support for this conclusion comes from the ability of the modulatory proctolin neuron (MPN), a projection neuron that suppresses the gastric mill rhythm via its inhibitory actions on MCN1 and CPN2, to inhibit the GPR-elicited gastric mill rhythm. Selective elimination of MCN1 and CPN2 access to the STG also prevents GPR activation of this rhythm. The VCN neurons also elicit the gastric mill rhythm by coactivating MCN1 and CPN2, but the GPR-elicited gastric mill rhythm is distinct. These distinct rhythms are likely to result partly from different MCN1 activity levels under these two conditions and partly from the presence of additional GPR actions in the STG. These results support the hypothesis that different sensory systems differentially regulate neuronal circuit activity despite their convergent actions on a single subpopulation of projection neurons.'|vDepartment of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074, USA.4-Blitz, D. M. Beenhakker, M. P. Nusbaum, M. P. 1529-2401 Journal Article J Neuroscilehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15601944Bohm, H. 1995VActivity of the stomatogastric system in free-moving crayfish, Orconectes limosus Raf.?QZoologyl99247-257-4-Bohm, H. Eitner, E. Messai, E. Heinzel, H. G. 1997,%Das nervensystem des flusskrebsmagens  Biologie in inserer Zeit. 27 56-64("Bohm, H. Messai, E. Heinzel, H. G. 1997LActivity of command fibres in free-ranging crayfish, Orconectes limosus Raf.5GNaturwissenschaften\84408-410lsZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10212401>8Withers, M. D. Kennedy, M. B. Marder, E. Griffith, L. C.Characterization of calcium/calmodulin-dependent protein kinase II activity in the nervous system of the lobster, Panulirus interruptushpjAmino Acid Sequence Animal Ca(2+)-Calmodulin Dependent Protein Kinase/*analysis/genetics Gene Expression Regulation, Enzymologic/physiology Lobsters/*enzymology Molecular Sequence Data Nervous System/*enzymology Phosphorylation Polymerase Chain Reaction Precipitin Tests Species Specificity Stomach/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.d]Nervous system tissue from Panulirus interruptus has an enzyme activity that behaves like calcium/calmodulin-dependent protein kinase II (CaM KII) This activity phosphorylates known targets of CaM KII, such as synapsin I and autocamtide 3. It is inhibited by a CaM KII-specific autoinhibitory domain peptide. In addition, this lobster brain activity displays calcium-independent activity after autophosphorylation, another characteristic of CaM KII. A cDNA from the lobster nervous system was amplified using polymerase chain reaction. The fragment was cloned and found to be structurally similar to CaM KII. Serum from rabbits immunized with a fusion protein containing part of this sequence immunoprecipitated a CaM KII enzyme activity and a family of phosphoproteins of the appropriate size for CaM KII subunits. Lobster CaM KII activity is found in the brain and stomatogastric nervous system including the commissural ganglia, commissures, stomatogastric ganglion and stomatogastric nerve. Immunoblot analysis of these same regions also identifies bands at an apparent molecular weight characteristic of CaM KII.'\VVolen Center, Brandeis University, Waltham, MA 02254, USA. mwithers@volen.brandeis.edu10212401Invert Neurosci 199834335-45.MLK.OJ93058830Chiba, C. Tazaki, K.d^Glutamatergic motoneurons in the stomatogastric ganglion of the mantis shrimp Squilla oratoria"Acetylcholine/physiology Animal Electrophysiology Ganglia/*physiology/ultrastructure Glutamates/*physiology Iontophoresis Membrane Potentials/physiology Motor Neurons/*physiology Neuromuscular Junction/physiology Neurotransmitters/physiology Shrimp/*physiology Support, Non-U.S. Gov't1. Transmitters of motoneurons in the stomatogastric ganglion (STG) of Squilla were identified by analyzing the excitatory neuromuscular properties of muscles in the posterior cardiac plate (pcp) and pyloric regions. 2. Bath and iontophoretic applications of glutamate produce depolarizations in these muscles. The pharmacological experiments and desensitization of the junctional receptors elucidate the glutamatergic nature of the excitatory junctional potentials (EJPs) evoked in the constrictor and dilator muscles. The reversal potentials for the excitatory junctional current (EJC) and for the glutamate-induced current are almost the same. 3. Some types of dilator muscle show sensitivity to both glutamate and acetylcholine (ACh) exogenously applied. The pharmacological evidence and desensitization of the junctional receptors indicate the glutamatergic nature of neuromuscular junctions in these dually sensitive muscles. The reversal potentials for the EJC and for the ACh-induced current are not identical. 4. Glutamate is a candidate as an excitatory neuro-transmitter at the neuromuscular junctions which the STG motoneurons named PCP, PY, PD, LA and VC make with the identified muscles. Kainic and quisqualic acids which act on glutamate receptors are potent excitants of these muscles. Extrajunctional receptors to ACh are present in two types of the muscle innervated by LA and VC. 5. Neurotransmitters used by the STG motoneurons of stomatopods are compared to those of decapods..J Comp Physiol [A] 1992 170x6y 773-869505364160Christie, A. E. Hall, C. Oshinsky, M. Marder, E.leBuccalin-like and myomodulin-like peptides in the stomatogastric ganglion of the crab Cancer borealislAmino Acid Sequence Animal Crabs/chemistry/*genetics Digestive System/innervation Ganglia, Invertebrate/physiology Immunohistochemistry Molecular Sequence Data Neuropeptides/*genetics/immunology/isolation & purification Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.d J Exp Biol 1994 193l 337-43f`http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.cob.org.uk/JEB/198/01/jeb9613.html0oF?Christie, A. Baldwin, D. Turrigiano, G. Graubard, K. Marder, E.eImmunocytochemical localization of multiple cholecystokinin-like peptides in the stomastogastric nervous system of the crab Cancer borealissThree anti-cholecystokinin antibodies were used to label the stomatogastric nervous system of the crab Cancer borealis. Labeled tissues were examined as whole mounts using laser scanning confocal microscopy. Although each of the anti-cholecystokinin antibodies labeled a variety of structures within the stomatogastric nervous system (including somata, fibers and neuropil), the pattern of labeling produced by each antibody was distinct. These results indicate that there is a family of cholecystokinin-like molecules that are differentially distributed among a subpopulation of the neurons in the stomatogastric nervous system of Cancer borealis. 1995 J Exp Biol 198 1m 263-71 Using Smart Source Parsingf`http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.cob.org.uk/JEB/198/12/jeb9908.html0r("Christie, A. Skiebe, P. Marder, E.XRMatrix ofneuromodulators in neurosecretory structures of the crab, Cancer borealisb\The crustacean stomatogastric ganglion, which is situated in the ophthalmic artery, can be modulated by both intrinsically released molecules and hormones. In the crab Cancer borealis, over a dozen neuroactive compounds have been identified in the input axons that project into the stomatogastric neuropil. However, little is known about the modulator content of the two major neurohemal organs, the sinus glands and the pericardial organs, in this crab. We now report the results of a series of immunocytochemical experiments designed to identify putative neurohormones in these tissues. We find that the majority of modulators present in the input axons of the stomatogastric ganglion are also present in at least one of the neurohemal organs. Specifically, allatostatin-like, buccalin-like, cholecystokinin-like, FLRFamide-like, GABA-like, locustatachykinin-like, myomodulin-like, proctolin-like, red pigment concentrating hormone-like and serotonin- like immunoreactivities are all present in both the stomatogastric neuropil and at least one of the neurohemal organs. Thus, these substances are likely to serve a dual role as both local and hormonal modulators of the stomatogastric network. Two other substances, - pigment dispersing hormone and crustacean cardioactive peptide, are not present in the stomatogastric neuropil, but -pigment dispersing hormone immunoreactivity is present in the sinus glands and crustacean cardioactive peptide immunoreactivity is present in the pericardial organs. It is likely that crustacean cardioactive peptide exerts its influence on the stomatogastric neural circuit via hormonal pathways. Double-labeling experiments show that the patterns of modulator co- localization present in the stomatogastric neuropil are different from those in the neurosecretory organs, suggesting that few rules of co- localization hold across these tissues. 1995 J Exp Biol 19812 2431-9 Using Smart Source Parsing97195750<6Christie, A. E. Baldwin, D. H. Marder, E. Graubard, K.|vOrganization of the stomatogastric neuropil of the crab, Cancer borealis, as revealed by modulator immunocytochemistry>7Animal Cholecystokinin/analysis Crabs/*metabolism Fluorescent Antibody Technique, Indirect Ganglia, Invertebrate/cytology/*metabolism Neurotransmitters/*analysis Oligopeptides/analysis Peptide Fragments/analysis Rabbits Serotonin/analysis Substance P/analysis Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.eWe used antibodies to a number of neuromodulatory substances, including serotonin, FLRF amide, red pigment-concentrating hormone, substance P, proctolin and cholecystokinin, to investigate the distribution of molecules similar to these substances in the stomatogastric ganglion of the crab, Cancer borealis. No immunoreactivity was seen in the region of the cell bodies that surrounds the neuropil and little was found in the core of the neuropil (where the primary neurites of the intrinsic neurons occupy most of the space). Instead, modulator immunolabel was densely packed in the more peripheral portion of the neuropil that surrounded the core. Within this peripheral neuropil, profiles appeared quite uniformly distributed. Double-labeling showed that there were limited differences in distribution between the labels examined in our study. The only immunolabeled structures that showed a distinct differential distribution within the stomatogastric neuropil were a population of >/=10 microm varicosities that arose from a pair of input fibers that we termed the large varicosity fibers. These varicosities were immunolabelled by antisera for three different peptides. Taken collectively, these data shows that there is a stereotyped distribution of modulator immunoreactivity within the crab stomatogastric neuropil. However, this segregation is more rudimentary than that reported for the intrinsic stomatogastric neurons.nCell Tissue Reso 1997 288r1s 135-48XZV<W 96033755& Cleland, T. A. Selverston, A. I.voGlutamate-gated inhibitory currents of central pattern generator neurons in the lobster stomatogastric ganglionAnimal Calcium/metabolism Cells, Cultured Central Nervous System/cytology/*physiology Electrophysiology Excitatory Amino Acid Agonists/pharmacology Excitatory Amino Acid Antagonists/pharmacology Extracellular Space/metabolism Ganglia, Invertebrate/cytology/*physiology Glutamic Acid/*physiology Lobsters/*physiology Neural Inhibition/*physiology Neurons/physiology Periodicity Receptors, Glutamate/physiology Stomach/*innervation Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Inhibitory glutamatergic neurotransmission is an elemental "building block" of the oscillatory networks within the crustacean stomatogastric ganglion (STG). This study constitutes the initial characterization of glutamatergic currents in isolated STG neurons in primary culture. Superfusion of 1 mM L-glutamate evoked a current response in 45 of 65 neurons examined. The evoked current incorporated two kinetically distinct components in variable proportion: a fast desensitizing component and a slower component. The current was mediated by an outwardly rectifying conductance increase and reversed at -48.8 +/- 5.3 mV. Reducing the external chloride concentration by 50% deflected the glutamate equilibrium potential (Eglu) by +14 mV, while increasing external potassium threefold shifted Eglu by up to +6 mV. Ibotenic acid fully activated both components of the glutamate response. Saturating concentrations of glutamate completely occluded neuronal responses to ibotenic acid, indicating that ibotenic acid was activating the same receptor(s) as glutamate. Millimolar concentrations of quisqualic acid, kainate, AMPA, and NMDA each failed to evoke any response. Picrotoxin (10(-4)M) completely blocked the glutamate response. Niflumic acid (100 microM) blocked > 80% of the desensitizing component and congruent to 50% of the sustained component. Reduction or elimination of extracellular calcium did not abolish the response. This study extends the ionic and pharmacological analysis of glutamatergic conductances in STG neurons. The currents described are consistent with glutamatergic inhibitory synaptic and agonist-evoked responses previously described in situ. We discuss their pharmacology, ionic mechanisms, and functional significance. J Neurosci 19951510 6631-98938647132 1996 Oct,&Inhibitory glutamate receptor channels 97-136 8 2Inhibitory glutamate receptors (IGluRs) are a family of ion channel proteins closely related to ionotropic glycine and gamma-aminobutyric acid (GABA) receptors; They are gated directly by glutamate; the open channel is permeable to chloride and sometimes potassium. Physiologically and pharmacologically, IGluRs most closely resemble GABA receptors; they are picrotoxin-sensitive and sometimes crossdesensitized by GABA. However, the amino acid sequences of cloned IGluRs are most similar to those of glycine receptors. Ibotenic acid, a conformationally restricted glutamate analog closely related to muscimol, activates all IGluRs. Quisqualate is not an IGluR agonist except among pulmonate molluscs and for a unique multiagonist receptor in the crayfish Austropotamobius torrentium. Other excitatory amino acid agonists are generally ineffective. Avermectins have several effects on IGluRs, depending on concentration: potentiation, direct gating, and blockade, both reversible and irreversible. Since IGluRs have only been clearly described in protostomes and pseudocoelomates, these effects may mediate the powerful antihelminthic and insecticidal action of avermectins, while explaining their low toxicity to mammals. IGluRs mediate synaptic inhibition in neurons and are expressed extrajunctionally in striated muscles. The presence of IGluRs in a neuron or muscle is independent of the presence or absence of excitatory glutamate receptors or GABA receptors in the cell. Generally, extrajunctional IGluRs in muscle have a higher sensitivity to glutamate than do neuronal synaptic receptors. Some extrajunctional receptors are sensitive in the range of circulating plasma glutamate levels, suggesting a role for IGluRs in regulating muscle excitability The divergence of the IGlu/GABA/Gly/ACh receptor superfamily in protostomes could become a powerful model system for adaptive molecular evolution. Physiologically and pharmacologically, protostome receptors are considerably more diverse than their vertebrate counterparts. Antagonist profiles are only loosely correlated with agonist profiles (e.g., curare-sensitive GABA receptors, bicuculline-sensitive AChRs), and pharmacologically identical receptors may be either excitatory or inhibitory, and permeable to different ions. The assumption that agonist sensitivity reliably connotes discrete, homologous receptor families is contraindicated. Protostome ionotropic receptors are highly diverse and straightforward to assay; they provide an excellent system in which to study and integrate fundamental questions in molecular evolution and adaptation.'>8Biology Department 0357, UCSD, La Jolla 92093-0357, USA.Cleland, T. A.@:97093085 0893-7648 Journal Article Review Review, Academic Mol NeurobiolAmino Acid Sequence Animal Chloride Channels/drug effects/*physiology Chlorides/metabolism Evolution, Molecular Excitatory Amino Acid Agonists/pharmacology Excitatory Amino Acid Antagonists/pharmacology Gene Expression Glutamic Acid/*physiology Human Invertebrates/physiology Ion Channel Gating/physiology Molecular Sequence Data Nerve Tissue Proteins/physiology Neurons/physiology Neurotoxins/pharmacology Phylogeny Potassium/metabolism Potassium Channels/drug effects/*physiology Receptors, Glutamate/classification/drug effects/*physiology Sequence Alignment Sequence Homology, Amino Acid Support, U.S. Gov't, P.H.S. Vertebrates/physiologyjdhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=893864798070674& Cleland, T. A. Selverston, A. I.f`Dopaminergic modulation of inhibitory glutamate receptors in the lobster stomatogastric ganglionAnimal Dopamine/physiology Ganglia, Invertebrate/cytology/physiology Lobsters/*physiology Neural Inhibition/physiology Neurons/physiology Patch-Clamp Techniques Receptors, Glutamate/physiology Stomach/innervation Support, U.S. Gov't, P.H.S.The intrinsic rhythmicity of the spiny lobster stomatogastric ganglion (STG) is strongly influenced by the strengths of the graded synapses between identified cells within the neural network. These synaptic strengths can be powerfully influenced by chemical neuromodulators such as dopamine and serotonin. Most of the intraganglionic chemical synapses in the STG are mediated by postsynaptic inhibitory glutamate receptors (IGluRs). To determine whether or not direct effects on these IGluRs contribute to the modulation of synaptic strength, unidentified STG neurons were extracted into primary culture and the effects of these aminergic neuromodulators on the glutamate-evoked membrane current were assessed. Dopamine (100 microM) reliably and significantly reduced the whole cell slope conductance of all IGluRs tested. Serotonin (20 microM) never affected the IGlu response, although it clearly altered other cellular membrane properties. Although all identified STG neurons may not conform to these observations, the data reveal a specific dopamine-activated modulatory pathway within cultured neurons that reduces IGluR slope conductance. The relationship between IGluR modulation and net synaptic modulation in situ contributes to an emerging model in which synaptic strengths can be multiply modulated at different functional sites, yielding a complex, distributed, and state- dependent regulatory structure.J Neurophysiol 1997786e 3450-2\.^[ lfhttp://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.jneurosci.org/cgi/content/full/18/7/278898171581F?Clemens, S. Massabuau, J. C. Legeay, A. Meyrand, P. Simmers, J.hIn vivo modulation of interacting central pattern generators in lobster stomatogastric ganglion: influence of feeding and partial pressure of oxygen Animal Anoxia/physiopathology Behavior, Animal/physiology Electrophysiology Feeding Behavior/drug effects/*physiology Ganglia, Invertebrate/drug effects/physiology Lobsters/*physiology Oxygen/*pharmacology Periodicity Stomach/innervation Support, Non-U.S. Gov'tif_The stomatogastric ganglion (STG) of the European lobster Homarus gammarus contains two rhythm-generating networks (the gastric and pyloric circuits) that in resting, unfed animals produce two distinct, yet strongly interacting, motor patterns. By using simultaneous EMG recordings from the gastric and pyloric muscles in vivo, we found that after feeding, the gastropyloric interaction disappears as the two networks express accelerated motor rhythms. The return to control levels of network activity occurs progressively over the following 1-2 d and is associated with a gradual reappearance of the gastropyloric interaction. In parallel with this change in network activity is an alteration of oxygen levels in the blood. In resting, unfed animals, arterial partial pressure of oxygen (PO2) is most often between 1 and 2 kPa and then doubles within 1 hr after feeding, before returning to control values some 24 hr later. In vivo, experimental prevention of the arterial PO2 increase after feeding leads to a slowing of pyloric rhythmicity toward control values and a reappearance of the gastropyloric interaction, without apparent effect on gastric network operation. Using in vitro preparations of the stomatogastric nervous system and by changing oxygen levels uniquely at the level of the STG within the range observed in the intact animal, we were able to mimic most of the effects observed in vivo. Our data indicate that the gastropyloric interaction appears only during a "free run" mode of foregut activity and that the coordinated operation of multiple neural networks may be modulated by local changes in oxygenation. J Neurosci 19981872788-99XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9779921*#Clemens, S. Meyrand, P. Simmers, J.,lfFeeding-induced changes in temporal patterning of muscle activity in the lobster stomatogastric systemAnimal Electromyography Feeding Behavior/*physiology Ganglia, Invertebrate/cytology/physiology Lobsters/*physiology Mastication/*physiology Muscles/*physiology Nerve Net/physiology Neurons/physiology Periodicity Support, Non-U.S. Gov't Time FactorsTMIn the lobster Homarus gammarus, rhythmic masticatory movements of the foregut gastric mill are generated by a small neural network in the stomatogastric ganglion. We have used EMG recordings from intact animals to analyse gastric network output in relation to cycle period before and after feeding. In pre-prandial conditions, muscles controlling lateral teeth closure and medial tooth protraction (driven by MG and GM motor neurons, respectively) express relatively constant, return stroke-like burst durations, but change to a variable-duration power stroke-like phenotype after feeding. In contrast, the LPG neuron- innervated lateral teeth opener muscle switches from power stroke to return stroke-like behavior. Thus alternate phases within a single motor program may invert their temporal properties according to the behavioral situation.'leLaboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and CNRS, UMR 5816, Arcachon, France.9779921 Neurosci Lett 1998 2542 65-8.:4Clemens, S. Massabuau, J. C. Meyrand, P. Simmers, J.vpChanges in motor network expression related to moulting behaviour in lobster: role of moult-induced deep hypoxiaThe well known rhythmically active pyloric neural network in intact and freely behaving lobsters Homarus gammarus was monitored prior to and following ecdysis. Despite long-lasting hormonal and metabolic alterations associated with this process, spontaneous pyloric network activity remained largely unaltered until the last 12-48 h before exuviation. At this time, the most notable change was a progressive lengthening of pyloric cycle period, which eventually attained 500-600 % of control values. It was only in the very last minutes before ecdysis that burst patterning became irregular and the otherwise strictly alternating motor sequence broke down. After the moult, coordinated rhythmicity was re-established within 10 min. Concomitant with these final changes in motor network expression at ecdysis was a drastic reduction in blood oxygen levels which led to a temporary near- anoxia. By imposing similarly deep hypoxic conditions both on intermoult animals and on the pyloric network in vitro, we mimicked to a large extent the moult-induced changes in pyloric network performance. Our data suggest that, despite major surrounding physiological perturbations, the pyloric network in vivo retains stable pattern-generating properties throughout much of the moulting process. Moreover, some of the most significant modifications in motor expression just prior to ecdysis can be related to a substantial reduction in oxygen levels in the blood.o'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and CNRS, UMR 5816, Avenue des Facultes, France and Laboratoire d'Ecophysiologie et Ecotoxicologie des Systemes Aquatiques, Universite Bordeaux I and CNRS, UMR 5805, Pla. 0010069971 J Exp Biol 1999 202e Pt 7817-27.shttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=0010069971 http://www.biologists.com/JEB/202/07/jeb1703.htmlec_N]ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=117187606:4Clemens, S. Massabuau, J. C. Meyrand, P. Simmers, J.b[A modulatory role for oxygen in shaping rhythmic motor output patterns of neuronal networksaAnimal Anoxia/physiopathology Feeding Behavior/physiology Ganglia, Invertebrate/cytology/physiology Lobsters Molting/physiology Motor Neurons/*physiology Neural Pathways/*physiology Oxygen/*pharmacokinetics Periodicity Support, Non-U.S. Gov't82It is becoming increasingly evident that O(2)-uptake in animal tissue is not only devoted to energy production. Here we review recent findings on a novel role of tissue oxygenation, notably in controlling the operation of neuronal networks in the central nervous system. Electrophysiological recordings in vivo and in vitro from rhythmically- active motor pattern generating networks in the lobster stomatogastric ganglion (STG) have revealed that oxygen is able to act in a manner equivalent to a classical neuromodulator. Local P(O(2)) variations within the low, but physiological range of 1-6 kPa are able to shape ongoing activity of these networks and therefore the motor behaviours in which they are involved. Oxygen's contribution to two of these, feeding and moulting, have been investigated. Importantly, the P(O(2)) effects are not related to hypoxic depression but are highly specific in terms of the network, neuron and even the synapse targeted. Our results are discussed in terms of functional significance and new research directions for mammalian physiology.'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux 1 & CNRS, Unite Mixte de Recherche 5816, Avenue des Facultes, 33405, Talence, France.o11718760Respir Physiol 2001 128o3c299-315.XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=2366869Cohen, L. Wu, J. Y.eOne neuron, many units?dxrAnimal Cerebellum/cytology Guinea Pigs In Vitro Neurons/*physiology Purkinje Cells/*physiology Synapses/physiology2366869M Nature 1990 346  6280 108-9.93107364@:Coleman, M. J. Nusbaum, M. P. Cournil, I. Claiborne, B. J.d]Distribution of modulatory inputs to the stomatogastric ganglion of the crab, Cancer borealisNRLAnimal Crabs/*physiology Fluorescent Antibody Technique Ganglia/*cytology/physiology Histocytochemistry Lysine/analogs & derivatives Microscopy, Electron Neuropeptides/immunology/metabolism/physiology Neurotransmitters/immunology/metabolism Oligopeptides/immunology/metabolism Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.The pyloric and gastric mill neural networks in the crustacean stomatogastric ganglion receive modulatory inputs from more anteriorly located ganglia via the stomatogastric nerve. In this study we employed biocytin backfilling and immunostaining, as well as electron microscopy, to determine the origin of these inputs in the crab, Cancer borealis. Fiber counts from electron micrographs of sections through the stomatogastric nerve showed that this nerve contains 55-60 medium to large diameter fibers (1-13 microns). These fibers were individually wrapped by several layers of membrane, presumably glial in origin. There was also a single cluster of jointly wrapped, small diameter ( 1 micron) fibers that may originate from peripheral sensory somata. Biocytin backfills revealed that approximately two thirds of the individually wrapped fibers in this nerve originate from somata in the other three ganglia of the stomatogastric nervous system, including the paired commissural ganglia and the single oesophageal ganglion. There were approximately 20 biocytin-labeled somata in each commissural ganglion and 3 somata in the oesophageal ganglion. An additional ten somata were localized to the stomatogastric ganglion itself. This accounts for nearly all of the medium to large diameter fibers in the stomatogastric nerve. We used double-labeling with backfills and immunocytochemistry to determine that there are two proctolin- immunoreactive neurons and four FMRFamide-like immunoreactive neurons among the biocytin-labeled neurons in each commissural ganglion. Both peptides modulate neural network activity in the stomatogastric ganglion.(ABSTRACT TRUNCATED AT 250 WORDS)t J Comp Neurolt 1992 325(4  581-94l rnntials*#Cournil, I. Meyrand, P. Moulins, M. 1990("Lobster stomatogastric GABA system @:Wiese, K. Krenz, W.-D. Tautz, J. Reichert, H. Mulloney, B.*$Frontiers in Crustacean Neurobiology Basel Birkhauser Verlag448-4547914897 3443 1994 Jun 15Dopamine in the lobster Homarus gammarus. I. Comparative analysis of dopamine and tyrosine hydroxylase immunoreactivities in the nervous system of the juveniley 455-69As a catecholamine, dopamine belongs to a class of molecules that have multiple transmitter and hormonal functions in vertebrate and invertebrate nervous systems. However, in the lobster, where many central neurons have been identified and the peripheral innervation pattern is well known, the distribution of dopamine-containing neurons has not been examined in detail. Therefore, immunocytochemical methods were used to identify neurons likely to contain dopamine and tyrosine hydroxylase in the central nervous system of the juvenile lobster Homarus gammarus. Approximately 100 neuronal somata stain for the catecholamine and/or its synthetic enzyme in the brain and ventral nerve cord. The systems of neurons labeled with dopamine and tyrosine hydroxylase antibodies have the following characteristics: 1) the two systems are nearly identical; 2) every segmental ganglion contains at least one pair of labeled neurons; 3) the positions and numbers of cell bodies labeled with each antiserum are similar in the various segmental ganglia; 4) six labeled neurons are anatomically identified; two interneurons from the brain project within the ventral cord to reach the last abdominal ganglion, two neurons from the commissural ganglia are presumably neurosecretory neurons, and two anterior unpaired medial abdominal neurons project to the hindgut muscles; and 5) no cell bodies are labeled in the stomatogastric ganglion, but fibers and terminals in the neuropil are stained. The remarkably small numbers of labeled neurons and the presence of very large labeled somata with far-reaching projections are distinctive features consistent with other modulatory aminergic systems in both vertebrates and invertebrates.'pjLaboratoire de Neurobiologie et Physiologie Comparees, CNRS et Universite de Bordeaux I, Arcachon, France.,&Cournil, I. Helluy, S. M. Beltz, B. S.("94342534 0021-9967 Journal Article J Comp NeurolAnimal Antibody Specificity Comparative Study Dopamine/immunology/*metabolism Ganglia, Invertebrate/enzymology/immunology/metabolism Immunohistochemistry Muscles/innervation Nephropidae/*metabolism Nervous System/enzymology/*metabolism Neural Pathways/cytology/immunology/metabolism Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tyrosine 3-Monooxygenase/immunology/*metabolismjdhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7914897e <d g 697215282("Combes, D. Simmers, J. Moulins, M.LFConditional dendritic oscillators in a lobster mechanoreceptor neuronezAnimal Dendrites/*physiology Lobsters Mechanoreceptors/*physiology Membrane Potentials/*physiology Support, Non-U.S. Gov't 1. Intra- and extracellular recordings were made from in vitro preparations of the lobster (Homarus gammarus) stomatogastric nervous system to study the nature and origin of pacemaker-like activity in a primary mechanoreceptor neurone, the anterior gastric receptor (AGR), whose two bilateral stretch-sensitive dendrites ramify in the tendon of powerstroke muscle GM1 of the gastric mill system. 2. Although the AGR is known to be autoactive, we report here that in 20% of our preparations, rather than autogenic tonic discharge, the receptor fired spontaneously in discrete bursts comprising three to ten action potentials and repeating at cycle frequencies of 0.5-2.5 Hz in the absence of mechanical stimulation. Intrasomatic recordings revealed that such rhythmic bursting was driven by slow oscillations in membrane potential, the frequency of which was voltage sensitive and dependent upon the level of stretch applied to the receptor terminals of the AGR. 3. Autoactive bursting of the AGR originated from an endogenous oscillatory mechanism in the sensory dendrites themselves, since (i) during both steady, repetitive firing and bursting, somatic and axonal impulses were always preceded 1:1 by dendritic action potentials, (ii) hyperpolarizing the AGR cell body to block triggering of axonal impulses revealed attenuated somatic spikes that continued to originate from the two peripheral dendrites, (iii) the timing of burst firing could be phase reset by brief electrical stimulation of either dendrite, and (iv) spontaneous bursting continued to be expressed by an AGR dendrite after physical isolation from the GM1 muscle and the stomatogastric nervous system. 4. Although a given AGR in vitro could switch spontaneously from dendritic bursting to tonic firing and vice versa, exogenous application of micromolar (or less) concentrations of the neuropeptide F1 (TNRNFLRFamide) to the dendritic membrane could rapidly and reversibly switch the receptor firing pattern from repetitive firing to the bursting mode. Exposure of the somatic and axonal membrane of the AGR to F1 was without effect, as were applications of other neuroactive substances such as serotonin, octopamine and proctolin. 5. We conclude that, as for many oscillatory neurones of the central nervous system, the intrinsic activity pattern of this peripheral sensory neurone may be dynamically conferred by extrinsic modulatory influences, presumably according to computational demands. Moreover, the ability of the AGR to behave as an endogenous burster imparts considerable integrative complexity since, in this activity mode, sensory coding not only occurs through the frequency modulation of on-going dendritic bursts but also via changes in the duration of individual bursts and their inherent spike frequencies.J Physiol (Lond) 1997 499 Pt 1 161-77("Combes, D. Meyrand, P. Simmers, J.f_Dynamic restructuring of a rhythmic motor program by a single mechanoreceptor neuron in lobster*#Animal Digestive System/innervation Ganglia, Invertebrate/*physiology In Vitro Lobsters Mechanoreceptors/*physiology Models, Neurological Motor Activity/*physiology Motor Neurons/physiology Muscle, Skeletal/innervation Neurons/*physiology Neurons, Afferent/physiology Support, Non-U.S. Gov'tF?We have explored the synaptic and cellular mechanisms by which a single primary mechanosensory neuron, the anterior gastric receptor (AGR), reconfigures motor output of the gastric mill central pattern generator (CPG) in the stomatogastric nervous system (STNS) of the lobster Homarus gammarus. AGR is activated in vivo by contraction of the medial tooth protractor muscle gm1 and accesses the gastric CPG via excitation of two in-parallel interneurons, the excitatory commissural gastric (CG) and the inhibitory gastric inhibitor (GI). In the spontaneously active STNS in vitro, weak firing of AGR in time with gastric mill motoneurons (GM) reinforces an ongoing type I gastric mill rhythm in which all gastric teeth power-stroke motoneurons are synchronously active. With strong AGR firing, these phase relationships switch abruptly to a type II pattern in which lateral and medial teeth power- stroke motoneurons fire in antiphase. Our results suggest that these bimodal actions on the gastric mill rhythm depend on the balance of firing of the CG and GI interneurons and that selection of the pathway resides in their different postsynaptic sensitivities to AGR. Whereas high intrinsic firing rates of the CG neuron ensure that the excitatory pathway predominates during low levels of sensory input, strong synaptic facilitation in the GI neuron favors the inhibitory pathway during high levels of receptor activity. Feedback from a single mechanosensory neuron is thus able, in an activity-dependent manner, to specify different motor programs from a single central pattern- generating network.a'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and Centre National de la Recherche Scientifique, Unite Mixte de Recherche 5816, 33405 Talence, France.h10212320http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10212320 http://www.jneurosci.org/cgi/content/full/19/9/3620l J Neurosci 1999199a3620-8.a("Combes, D. Meyrand, P. Simmers, J.d^Motor pattern specification by dual descending pathways to a lobster rhythm-generating network<5Animal Efferent Pathways/physiology Electric Stimulation Electromyography Evoked Potentials Ganglia, Invertebrate/*physiology In Vitro Interneurons/physiology Lobsters Mastication/*physiology Motor Activity/*physiology Motor Neurons/physiology Nerve Net/*physiology Neurons/*physiology Support, Non-U.S. Gov'tIn the European lobster Homarus gammarus, rhythmic masticatory movements of the three foregut gastric mill teeth are generated by antagonistic sets of striated muscles that are driven by a neural network in the stomatogastric ganglion. In vitro, this circuit can spontaneously generate a single (type I) motor program, unlike in vivo in which gastric mill patterns with different phase relationships are found. By using paired intrasomatic recordings, all elements of the gastric mill network, which consists mainly of motoneurons, have been identified and their synaptic relationships established. The gastric mill circuit of Homarus is similar to that of other decapod crustaceans, although some differences in neuron number and synaptic connectivity were found. Moreover, specific members of the lobster network receive input from two identified interneurons, one excitatory and one inhibitory, that project from each rostral commissural ganglion. Integration of input from these projection elements is mediated by synaptic interactions within the gastric mill network itself. In arrhythmic preparations, direct phasic stimulation of the previously identified commissural gastric (CG) interneuron evokes gastric mill output similar to the type I pattern spontaneously expressed in vitro and in vivo. The newly identified gastric inhibitor interneuron makes inhibitory synapses onto a different subset of gastric mill neurons and, when activated with the CG neuron, drives gastric mill output similar to the type II pattern that is only observed in the intact animal. Thus, two distinct phenotypes of gastric mill network activity can be specified by the concerted actions of parallel input pathways and synaptic connectivity within a target central pattern generator.'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and Centre National de la Recherche Scientifique, Unite Mixte de Recherche 5816, 33405 Talence, France.10212319http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10212319 http://www.jneurosci.org/cgi/content/full/19/9/3610 J Neurosci 19991993610-9.8!JTuw>f "h 932536546/Combes, D. Simmers, J. Nonnotte, L. Moulins, M.rpjTetrodotoxin-sensitive dendritic spiking and control of axonal firing in a lobster mechanoreceptor neuroneAction Potentials/drug effects/physiology Animal Axons/*physiology Dendrites/*physiology Lobsters Mechanoreceptors/*physiology Support, Non-U.S. Gov't Tetrodotoxin/*pharmacology 1. A primary mechanosensory neurone, the anterior gastric receptor (AGR) associated with gastric mill muscle in the lobster foregut was examined in vitro with extra- and intra-cellular recording techniques to understand processes of dendritic integration and dendro-axonal communication. 2. AGR has a 'T'-shaped geometry; its two long (> 3 mm) primary dendrites project distally to spatially separate, stretch sensitive terminals and converge centrally onto a common apical neurite that leads to a bipolar soma and single axon. 3. The receptor's bilateral dendrites are independently capable of generating action potentials. These appear to be Na+ dependent since they are blocked by tetrodotoxin, but not by Co2+ or a lack of Ca2+ in the bath saline. 4. Both dendrites are autogenically active, although impulses in the dendrite with the higher intrinsic excitability may cross over and activate the trigger zone on the contralateral side. Moreover, spikes arising on either dendrite do not actively invade the soma, but are conveyed as decremented potentials to a third trigger zone on the initial axon segment. 5. Focal applications of TTX (tetrodotoxin) demonstrated the existence and allowed precise definition of a central membrane compartment of AGR that appears to lack in functional Na+ channels. This inexcitable region includes the soma, the apical neurite and the central branch point of the two dendrites. A failure to observe collision block of bilateral dendritic potentials as they traverse the neurite supported this conclusion. 6. Horseradish peroxidase injections and staining revealed two morphological features of the apical neurite that differed markedly from other regions of the cell. In addition to a relatively large diameter, the neurite's plasma membrane is heavily convoluted and coiled to form a lamellar transverse profile. This latter feature may itself contribute to membrane inexcitability while the former is consistent with an elevated space constant for electrotonic conduction. 7. It is concluded that the inhomogeneous distribution of membrane excitability in AGR enhances the integrative capability of the receptor's dendrites, permitting mechanical input at diverse loci to be encoded and processed prior to transformation into axonal discharge.J Physiol (Lond) 1993 460581-60296167628("Combes, D. Simmers, J. Moulins, M.\VStructural and functional characterization of a muscle tendon proprioceptor in lobster Animal Biomechanics Dendrites/ultrastructure Gastrointestinal Motility/*physiology Lobsters/*anatomy & histology/physiology Neurons, Afferent/physiology/*ultrastructure Proprioception/*physiology Support, Non-U.S. Gov't Tendons/*anatomy & histology/physiologyiHBA morphological and electrophysiological study was made on a unique primary mechanosensory neuron, the anterior gastric receptor (AGR), previously shown to arise from power-stroke muscle gm1 of the gastric mill system in the lobster foregut. Ultrastructural analysis of horseradish peroxidase injected AGR demonstrated that its peripheral dendrites do not ramify in muscle but are confined strictly to the connective tissue/epidermal interface in the tendon of gm1. These terminals are rich in mitochondria and at their very endings are free of glial cell wrapping, suggesting that they are the site at which mechano-transduction occurs. Extracellular axonal recordings from an in vitro neuromuscular preparation consisting of the gm1 muscle still attached to the stomatogastric nervous system, revealed that AGR is activated by passive stretch of gm1. The response to ramp stimuli displays dynamic and static components, both of which increase with the amplitude of applied stretch, while the dynamic component is also velocity sensitive. AGR is also activated by muscle contraction here elicited either by application of exogenous acetylcholine, the excitatory neurotransmitter for gm1, or by electrical stimulation of the motoneurons (GM) themselves. Consistent with a receptor lying in- series with its muscle, therefore, the effective stimulus of AGR in vivo is probably an increase in tension exerted on the tendon during active muscle contraction. In neuromuscular preparations including the bilateral commissural ganglia, stretching gm1 reflexly activates GM motoneurons at low stimulus strengths but leads to an inactivation of GM motoneurons at high stimulus strengths. This is consistent with earlier findings that both responses can be elicited by direct electrical stimulation of AGR. The functional implications of AGR's anatomical relationship with muscle gm1, the receptor's response properties, and its central effects on motor output to gm1 are discussed. Comparison is also drawn between this first reported example of a true tendon receptor in invertebrates and muscle receptors of vertebrates. J Comp Neurol 1995 3632 221-34 , $~,(Biogenic Amines/pharmacology/*physiology,'Biogenic Amines/pharmacology/physiology$Biogenic Monoamines/*physiologyBiological Clocks Biological Clocks/*physiology0*Biological Clocks/drug effects/*physiology Biological Clocks/physiologyBiological Transport Biomechanics Biotin/analogs & derivatives BistabilityBistable elementBlood Glucose/*physiologyBlood PhysiologyBlood Vessels/physiologyBlood/physiologyBlotting, Western Brachyura,)Brachyura/*anatomy & histology/physiologyBrain Chemistry Brain Chemistry/*physiologyBrain/*physiology Brain/cytology/*physiologyBrain/cytology/physiology Brain/embryology/*physiologyBrain/physiologyBromodeoxyuridine Bungarotoxins/pharmacology Bursting@=Ca(2+)-Calmodulin Dependent Protein Kinase/*analysis/geneticsCadmium/metabolismCaffeine/*pharmacologyCalcitonin/*analysis@;Calcitonin/administration & dosage/*pharmacology/physiology,&Calcium Channel Blockers/*pharmacology(%Calcium Channel Blockers/pharmacology0-Calcium Channels, L-Type/genetics/*metabolism0,Calcium Channels, P-Type/genetics/metabolism$Calcium Channels/*drug effects Calcium Channels/*physiology Calcium Channels/drug effects,)Calcium Channels/drug effects/*physiology,(Calcium Channels/drug effects/physiology Calcium Channels/metabolism Calcium Channels/physiology Calcium Signaling/physiology0-Calcium-Binding Proteins/genetics/*metabolismCalcium/*metabolism$ Calcium/*metabolism/pharmacologyCalcium/*physiologyCalcium/metabolism$Calcium/metabolism/*physiologyCalcium/pharmacologyCalcium/physiology(#Calmodulin/antagonists & inhibitors("Carbachol/antagonists & inhibitorsCarbon Isotopes$Cations, Divalent/pharmacologyCatsCell CommunicationCell Compartmentation Cell Count$Cell Differentiation/physiology Cell LineCell Membrane/*physiologyCell Membrane/enzymologyCell Membrane/metabolismCell Membrane/physiology,'Cell Membrane/physiology/ultrastructureCell Separation Cell Survival Cell Survival/drug effectsCells, Cultured("Central nervous system Congresses.("Central Nervous System/*physiology0+Central Nervous System/cytology/*physiologyHCCentral Nervous System/drug effects/enzymology/growth & development0,Central Nervous System/immunology/physiologyCerebellum/cytology$Cerebral Ventricles/physiologyCesium/pharmacology Chelating Agents/metabolism Chemistry0*Chloride Channels/drug effects/*physiologyChlorides/*metabolismChlorides/metabolismChlorides/pharmacologyChlorides/physiology Chlorisondamine/*pharmacology Chlorisondamine/*physiology,)Cholecystokinin/*isolation & purificationCholecystokinin/analysis@=Cholecystokinin/analysis/antagonists & inhibitors/isolation &DACholecystokinin/antagonists & inhibitors/pharmacology/*physiology,&Cholecystokinin/immunology/*metabolism,&Cholecystokinin/metabolism/*physiology CholineCholine/*metabolismCholine/metabolism0+Cholinergic Fibers/drug effects/*physiology,&Cholinesterase Inhibitors/pharmacology($Chromatography, High Pressure LiquidCircadian Rhythm Circadian Rhythm/*physiology Circadian Rhythm/drug effectsCitrulline/metabolismCloning, MolecularCockroaches/chemistryCockroaches/drug effectsComparative Study Computational Biology/methodsComputer SimulationComputer Systems Computers Conserved Sequence/physiologycrabCrabsCrabs/*analysis Crabs/*anatomy & histology(%Crabs/*anatomy & histology/physiology$Crabs/*drug effects/*physiologyCrabs/*metabolismCrabs/*physiologyCrabs/*ultrastructure(%Crabs/anatomy & histology/*physiology($Crabs/anatomy & histology/metabolismmki Meyrand, P.Coombs, E.G. Allen, J.A. 1978eThe functional morphology of the feeding appendages and gut of Hippolyte varians (Crustacea: Natania)A?PZool J Linn Soc Lond64261-282850242326/Cournil, I. Geffard, M. Moulins, M. Le Moal, M.nb[Coexistence of dopamine and serotonin in an identified neuron of the lobster nervous systemcAnimal Dopamine/*analysis/metabolism Ganglia/*analysis/metabolism Histocytochemistry Immunochemistry Lobsters/*metabolism Radioimmunoassay Serotonin/*analysis/metabolism Support, Non-U.S. Gov'tHThe combination of several analytical methods, i.e. chemical analysis (high performance liquid chromatography), biochemical analysis (radioimmunoassay) and immunohistochemistry, has shown that a single neuron can contain two 'classical' neurotransmitters.m Brain Rese 1984 310u2o397-400 91056330*#Cournil, I. Meyrand, P. Moulins, M.ijcIdentification of all GABA-immunoreactive neurons projecting to the lobster stomatogastric ganglionm Animal Digestive System/chemistry/innervation Evoked Potentials/physiology Fluorescent Dyes Ganglia/chemistry/cytology GABA/*analysis Immunoenzyme Techniques Isoquinolines Lobsters/*analysis/cytology Microelectrodes Neural Pathways/chemistry Neurons/chemistry NickelThe stomatogastric ganglion of lobsters (Homarus or Jasus) contains a large number of gamma-aminobutyric acid-immunoreactive processes originating from ten fibres in the single input nerve, the stomatogastric nerve. The cell bodies and axonal pathways of these ten fibres have been identified using gamma-aminobutyric acid immunohistochemistry in combination with Lucifer Yellow staining (double labelling) and nickel chloride backfilling (selective gamma- aminobutyric acid immunoinhibition). It is shown that eight gamma- aminobutyric acid-immunoreactive neurons project to the stomatogastric ganglion: gamma-aminobutyric acid neurons 1 and 2, found posterior to the oesophageal ganglion, entering the stomatogastric nerve via the oesophageal nerve as well as sending an axonal branch into each superior oesophageal nerve; gamma-aminobutyric acid neurons 3 and 4, found anterior to the oesophageal ganglion, each sending an axonal branch into each inferior oesophageal nerve to reach the stomatogastric nerve via the commissural ganglion and the superior oesophageal nerve; and gamma-aminobutyric acid neurons 5 and 6, found in each commissural ganglion, projecting into the stomatogastric nerve via the inferior oesophageal nerve, the oesophageal ganglion and the oesophageal nerve. These gamma-aminobutyric acid-immunoreactive neurons were also characterized by electrophysiological methods coupled with Lucifer Yellow labelling, and their picrotoxin-sensitive effects on several stomatogastric ganglion neurons were demonstrated. The present results provide a firm basis for further studies concerning the physiological significance of one class of neurochemically-defined input neurons to stomatogastric ganglion networks. J Neurocytol 1990194 478-93 dl95123456VOHarris-Warrick, R. M. Coniglio, L. M. Barazangi, N. Guckenheimer, J. Gueron, S.tmDopamine modulation of transient potassium current evokes phase shifts in a central pattern generator networkiAnimal Cesium/pharmacology Dopamine/*pharmacology Electric Conductivity Ganglia, Invertebrate/physiology Gastrointestinal Motility/physiology Lobsters Models, Neurological Neurons/drug effects/physiology *Periodicity Potassium/*physiology Stomach/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology 4-Aminopyridine/pharmacologydBath application of dopamine modifies the rhythmic motor pattern generated by the 14 neuron pyloric network in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. Among other effects, dopamine excites many of the pyloric constrictor (PY) neurons to fire at high frequency and phase-advances the timing of their activity in the motor pattern. These responses arise in part from direct actions of dopamine to modulate the intrinsic electrophysiological properties of the PY cells, and can be studied in synaptically isolated neurons. The rate of rebound following a hyperpolarizing prestep and the spike frequency during a subsequent depolarization are both accelerated by dopamine. Based on theoretical simulations, Hartline (1979) suggested that the rate of postinhibitory rebound in stomatogastric neurons could vary with the amount of voltage- sensitive transient potassium current (IA). Consistent with this prediction, we found that dopamine evokes a net conductance decrease in synaptically isolated PY neurons. In voltage clamp, dopamine reduces IA, specifically by reducing the amplitude of the slowly inactivating component of the current and shifting its voltage activation curve in the depolarized direction. 4-Aminopyridine, a selective blocker of IA in stomatogastric neurons, mimics and occludes the effects of dopamine on isolated PY neurons. A conductance-based mathematical model of the PY neuron shows appropriate changes in activity upon quantitative modification of the IA parameters affected by dopamine. These results demonstrate that dopamine excites and phase-advances the PY neurons in the rhythmic pyloric motor pattern at least in part by reducing the transient K+ current, IA. J Neurosci 199515 1 Pt 1 342-58uy{Jzx 89257515"Dickinson, P. S. Marder, E. Peptidergic modulation of a multioscillator system in the lobster. I. Activation of the cardiac sac motor pattern by the neuropeptides proctolin and red pigment-concentrating hormone.(Action Potentials Animal Female Heart/drug effects/*physiology Immunohistochemistry Lobsters/*physiology Male Motor Neurons/drug effects/physiology Neural Pathways Oligopeptides/*pharmacology Peptides/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.zs1. The cardiac sac motor pattern consists of slow and irregular impulse bursts in the motor neurons [cardiac sac dilator 1 and 2 (CD1 and CD2)] that innervate the dilator muscles of the cardiac sac region of the crustacean foregut. 2. The effects of the peptides, proctolin and red pigment-concentrating hormone (RPCH), on the cardiac sac motor patterns produced by in vitro preparations of the combined stomatogastric nervous system [the stomatogastric ganglion (STG), the paired commissural ganglia (CGs), and the oesophageal ganglion (OG)] were studied. 3. Bath applications of either RPCH or proctolin activated the cardiac sac motor pattern when this motor pattern was not already active and increased the frequency of the cardiac sac motor pattern in slowly active preparations. 4. The somata of CD1 and CD2 are located in the esophageal and stomatogastric ganglia, respectively. Both neurons project to all four of the ganglia of the stomatogastric nervous system. RPCH elicited cardiac sac motor patterns when applied to any region of the stomatogastric nervous system, suggesting a distributed pattern generating network with multiple sites of modulation. 5. The anterior median (AM) neuron innervates the constrictor muscles of the cardiac sac. The AM usually functions as a part of the gastric mill pattern generator. However, when the cardiac sac is activated by RPCH applied to the stomatogastric ganglion, the AM neuron becomes active in antiphase with the cardiac sac dilator bursts. This converts the cardiac sac motor pattern from a one-phase rhythm to a two-phase rhythm. 6. These data show that a neuropeptide can cause a neuronal element to switch from being solely a component of one neuronal circuit to functioning in a second one as well. This example shows that peptidergic "reconfiguration" of neuronal networks can produce substantial changes in the behavior of associated neurons.J Neurophysiol 1989614 833-4490174301,&Dickinson, P. S. Mecsas, C. Marder, E.B;Neuropeptide fusion of two motor-pattern generator circuits2,Animal Ganglia/*physiology Invertebrate Hormones/*physiology Lobsters Membrane Potentials Models, Neurological Motor Neurons/*physiology Nervous System/physiology Nervous System Physiology Neuropeptides/*physiology Oligopeptides/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Animals make many different movements as circumstances dictate. These movements often involve the coordination of several neural networks, the output of which can be changed by modulatory substances. Here we report that the neuropeptide red pigment concentrating hormone modulates the interactions between two rhythmic pattern-generating networks in the lobster stomatogastric nervous system. Red pigment concentrating hormone markedly enhances the amplitude of synaptic interactions between elements of two pattern-generating networks--the cardiac sac and the gastric mill. Consequently, two networks operating under some circumstances virtually independently can be fused into one functional unit operating differently from either of the two original networks. These results show how a neuropeptide can alter the functional configuration of a neural network so that widely disparate outputs can be produced by the same neurons. Nature 1990 344 6262 155-8"Dickinson, P.S. Moulins, M. 1992d^Interactions and combinations between different networks in the stomatogastric nervous system. BDynamic Biological Networks: The Stomatogastric Nervous System  Cambridge, MA  MIT Press139-1609328667981Dickinson, P. S. Mecsas, C. Hetling, J. Terio, K.rnhThe neuropeptide red pigment concentrating hormone affects rhythmic pattern generation at multiple sitesngAnimal Central Nervous System/*physiology Female Ganglia/*physiology Gastrointestinal Motility/*physiology Invertebrate Hormones/*physiology Lobsters/*physiology Male Membrane Potentials/physiology Nerve Fibers/physiology Nerve Net/*physiology Neurons/physiology Oligopeptides/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Tissue Culture 1. The cardiac sac network, which controls the rhythmic contractions of the cardiac sac in the foregut of crustaceans, is distributed throughout the stomatogastric nervous system, including the oesophageal ganglion (OG), the commissural ganglia (CGs), and the stomatogastric ganglion (STG). A red pigment-concentrating hormone (RPCH)-like peptide is likewise widely distributed. 2. The effects that bath application of the neuropeptide RPCH to the different ganglia has on the cardiac sac pattern were studied. 3. RPCH applied to the STG, the OG, or the CGs elicited bursting activity in all the known components of the cardiac sac pattern, including the two motor neurons, cardiac sac dilators 1 and 2 (CD1 and CD2), and the inferior ventricular nerve (ivn) fibers. 4. A cardiac sac pattern was also elicited when RPCH was applied to either the STG, the OG, or the CGs after synapses in that ganglion had been blocked by low Ca2+ saline containing 20 mM Co2+. 5. These data suggest that the ivn fibers are sensitive to RPCH and respond to it by generating bursting activity at or near their terminals in all four ganglia. 6. Application of RPCH to either the STG or the OG also caused an increase in the amplitude of the postsynaptic potential (PSP) from the ivn fibers to both CD1 and CD2. The increase was largest in the ganglion to which the RPCH was applied. 7. Repeated stimulation of the ivn, mimicking the bursts that occur during cardiac sac activity, also caused an increase in PSP amplitude, and so facilitation resulting from activation of ivn bursting could account for a portion of the increased amplitude seen in RPCH.(ABSTRACT TRUNCATED AT 250 WORDS)J Neurophysiol 1993695i1475-83i\Vhttp://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://biomednet.com/article/nb561496403286Dickinson, P. S.6/Interactions among neural networks for behavior}Animal Behavior/*physiology Behavior, Animal/*physiology Human Nerve Net/cytology/*physiology Neurons/physiology *Periodicityt(!In recent years, as our understanding of the pattern-generating networks responsible for a variety of behaviors has increased, the interactions of multiple neural networks have been examined in a number of systems. These studies have shown that functionally related pattern generators can interact extensively, and that the extent to which two or more of these networks interact is not fixed, but can be altered by neuromodulators. Furthermore, a number of studies have begun to elucidate the mechanisms responsible for those interactions. In the crustacean stomatogastric system, for example, neurons can switch between different pattern generators, and whole networks can fuse into single patterns. In addition, several networks can be dismantled, and their components used to generate a new network. The mechanisms responsible for these changes are the same as those involved in other circuit re-configurations, namely alterations of both intrinsic membrane properties of component neurons and alterations in the strength of synapses within the networks.uCurr Opin Neurobiol  19955e6i 792-8r B93057722$Elson, R. C. Selverston, A. I.Mechanisms of gastric rhythm generation in the isolated stomatogastric ganglion of spiny lobsters: bursting pacemaker potentials, synaptic interactions, and muscarinic modulationAnimal Electrophysiology Ganglia/*physiology In Vitro Lobsters/*physiology Muscarine/*metabolism Nerve Net/physiology Neural Inhibition Neural Pathways/physiology Neurons/physiology *Periodicity Stomach/*innervation/physiology Support, U.S. Gov't, P.H.S. Synapses/*physiologya 1. The gastric central pattern generator (CPG), located in the stomatogastric ganglion (STG) of the spiny lobster (Panulirus interruptus), is nonrhythmic when deprived of neuromodulatory inputs from anterior ganglia. Leaving these inputs intact in vitro can sustain a gastric rhythm but also introduces numerous, uncontrolled and largely unknown modulatory and synaptic influences that greatly complicate analysis of this CPG. 2. Here we induced gastric rhythms in the isolated STG, by superfusing a specific modulator, the muscarinic agonist, pilocarpine. Muscarinic agents sustain vigorous gastric rhythms in the isolated STG. Our aim was to analyze the pattern- generating functions of the restricted gastric circuit, free of complicating influences from other ganglia, and under specific (muscarinic) modulation. 3. We used combinations of multiple cell hyperpolarizations, photodeletions, and synaptic blockade by picrotoxin to assess the pattern-generating role of individual gastric neurons and to study the activity of subcircuits. 4. Four identified gastric neurons [lateral gastric (LG), dorsal gastric (DG), 2 electrically coupled lateral posterior gastric (2LPGs)] acted as pattern-generating cells. They showed bursting pacemaker potentials (BPPs), i.e., plateau (or driver) potentials that underlay bursts of axonal spikes and slow, interburst depolarizing potentials that underlay repetitive burst activity. LG and DG, at least, became conditional bursters, able to burst repetitively because of intrinsic oscillations. The other gastric neurons behaved mainly as follower cells and derived their rhythmic bursting from synaptic coupling to the pattern-generator cells and from their own intrinsic (but nonoscillatory) properties. 5. The pattern- generating neurons form a novel "kernel" circuit that works by the cooperative interaction of cellular properties and synaptic connectivity. 6. This study constitutes the first complete and fully consistent analysis of pattern generation in the gastric network of the isolated STG. These mechanisms pertain to muscarinic rhythms in particular but also, we suggest, to gastric rhythm generation and CPG function in general. We suggest that 1) rhythmicity normally depends on the induction of bursty membrane properties in at least some component neurons; 2) different subcircuits can produce rhythmic patterns and may be activated by different modulators; and 3) the gastric network shares several important "building blocks" with CPGs that have been analyzed in other systems. 7. Muscarinic inputs are implicated as an important gastric regulator. We compare these responses with the reported modulatory actions of the anterior pyloric modulator (AMP), an identified, putatively cholinergic input interneuron that may act via muscarinic mechanisms.J Neurophysiol 1992683890-907 t~| }rpsqoj96154815<5Cournil, I. Casasnovas, B. Helluy, S. M. Beltz, B. S.zsDopamine in the lobster Homarus gammarus: II. Dopamine-immunoreactive neurons and development of the nervous systemiAnimal Antibody Specificity Dopamine/*analysis/immunology Embryo, Nonmammalian/chemistry Eye/innervation/ultrastructure Female Ganglia, Invertebrate/chemistry Immunohistochemistry Larva/chemistry Lobsters/*chemistry/*physiology Muscles/innervation Nervous System/physiology Nervous System Physiology Neuronal Plasticity/physiology Neurons/*chemistry Neurotransmitters/*analysis/immunologyDopamine-immunoreactive neurons were revealed in lobster embryos, larvae, and postlarvae, and staining patterns were compared to neuronal labeling in the juvenile lobster nervous system (Cournil et al. [1994] J. Comp. Neurol. 344:455-469). Dopamine immunoreactivity is first detected by midembryonic life in 35-40 neuronal somata located anteriorly in brain and subesophageal ganglion. When the lobsters assume a benthic life during the first postlarval stage, an average of 58 cell bodies are labeled. The acquisition of dopamine in lobster neurons is a protracted event spanning embryonic, larval, and postlarval life and finally reaching the full complement of roughly 100 neurons in juvenile stages. Some of the dopaminergic neurons previously identified in the mature nervous system, such as the paired Br cells, L cells, and mandibular cells, are labeled in embryos and persist throughout development. In contrast, other neurons stain transiently for dopamine during the developmental period, but, by the adult stage, these neurons are no longer immunoreactive. Such transiently labeled neurons project to the foregut, the thoracic dorsal muscles, the neurohormonal pericardial plexus, and the pericardial pouches. It is proposed that these neurons are alive and functioning in adult lobster but that dopamine levels have been abolished, providing that neurotransmitter status is a dynamic, changing process. J Comp Neurol  1995 362u1e 1-16 Dall, W. Moriarty, D.J.W. 19834-Functional aspects of nutrition and digestion  Mantel, L.H.NGThe Biology of Crustacea: Internal Anatomy and Physiological Regulation New York Academic Press5215-26169137086"Dando, M. R. Laverack, M. S.b\The anatomy and physiology of the posterior stomach nerve (p.s.n.) in some decapod crustaceaAction Potentials Animal *Autonomic Nervous System/anatomy & histology/physiology *Crustacea Electric Stimulation Gastrointestinal System/*innervation Receptors, Sensory Reflex Proc R Soc Lond B Biol Sci 1969 171n25 465-82"Dando, M.R. Selverston, A.I. 1972dCommand fibres from the supra-oesophageal ganglion to the stomatogastric ganglion in Panulirus argusTJ Comp Physiol78138-175("Dando, M.R. Chanussot, B. Nagy, F. 1974Activation of command fibres to the stomatogastric ganglion by input form a gastric mill proprioceptor in the crab, Cancer pagurustMar Behav Physiol2197-228"Dando, M. R. Maynard, D. M.  1974NThe sensory innervation of the foregut of Panulirus argus (Decapoda Crustacea)*9Mar Behav Physiol2283-305f81241613,%Dickinson, P. S. Nagy, F. Moulins, M.4TMInterganglionic communication by spiking and nonspiking fibers in same neuronfAnimal Esophagus/innervation Female Ganglia/*physiology Lobsters/physiology Male Motor Neurons/physiology Nerve Fibers/*physiology Neurons/ultrastructure Support, Non-U.S. Gov't *Synaptic TransmissionJ Neurophysiol 1981456u1125-38S84009538 Dickinson, P. S. Nagy, F.aControl of a central pattern generator by an identified modulatory interneurone in crustacea. II. Induction and modification of plateau properties in pyloric neuronesAnimal Digestive System/*innervation Electric Conductivity Esophagus/innervation Female Interneurons/*physiology Lobsters Male Membrane Potentials Support, Non-U.S. Gov'tIn the isolated stomatogastric nervous system of the lobster Fasus lalandii, the strong modifications of the pyloric motor pattern induced by firing of the single anterior pyloric modulator neurone (APM) are due primarily to modulation by APM activity of the regenerative membrane properties which are responsible for the 'burstiness' of all the pyloric neurones and particularly of the non-pacemaker neurones (constrictor motoneurones). This modulation has been studied under experimental conditions where the main extrinsic influences usually received by the pyloric constrictor neurones (intra-network synaptic interactions, activity of pacemaker neurones, and phasic central inputs from two premotor centres) are minimal. Under these conditions a brief discharge of neurone APM induces long plateaus of firing in all of the pyloric neurones. The non-pacemaker neurones of the pyloric network are not simply passive follower neurones, but can produce regenerative depolarizations (plateau potentials) during which the neurones fire spikes. The ability of the pyloric constrictor neurones to produce plateau potentials (plateau properties) contributes greatly to the generation of the rhythmical pyloric motor pattern. When these neurones spontaneously express their plateau properties, firing of neurone APM amplifies these properties. When most of the central inputs usually received by the pyloric constrictor neurones are experimentally suppressed, these neurones can no longer produce plateau potentials. In such conditions, firing of the single modulatory neurone APM can reinduce plateau properties of the pyloric constrictor neurones. In addition, firing in APM neurone slows down the active repolarization phase which terminates the plateau potentials of pyloric constrictor neurones. This effect is long-lasting and voltage-dependent. Modulation by APM of the plateau properties of the pyloric neurones also changes the sensitivity of these neurones to synaptic inputs. This effect can explain the strong modifications that an APM discharge exerts on a current pyloric motor pattern. Moreover, it might render the motoneurones of the pyloric pattern generator more sensitive to inputs from a command oscillator, and contribute to switching on the pyloric motor pattern. J Exp Biol 1983 105 59-82*$Dickinson, P.S. Nagy, F. Moulins, M. 1988Control of central pattern generators by an identified neurone in crustacea: Activation of the gastric mill motor pattern by a neurone known to modulate the pyloric network J Exp Biol 136 53-87Dickinson, P.S. 1989rkMotor program selection in the arthropod stomatogastric nervous system: Motor output in a modulated network .(Erber, J Menzel, R. Pfluger, H. Todt, D.$Neural Mechanisms of Behavior  Stuttgart Georg Thieme Verlage184-1858 8wLv97218396D=Dickinson, P. S. Fairfield, W. P. Hetling, J. R. Hauptman, J.nNeurotransmitter interactions in the stomatogastric system of the spiny lobster: one peptide alters the response of a central pattern generator to a second peptide(Animal Dose-Response Relationship, Drug Female Gastrointestinal System/*drug effects/physiology Lobsters Male Neurotransmitters/*pharmacology Oligopeptides/*pharmacology Patch-Clamp Techniques Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.Two of the peptides found in the stomatogastric nervous system of the spiny lobster, Panulirus interruptus, interacted to modulate the activity of the cardiac sac motor pattern. In the isolated stomatogastric ganglion, red-pigment-concentrating hormone (RPCH), but not proctolin, activated the bursting activity in the inferior ventricular (IV) neurons that drives the cardiac sac pattern. The cardiac sac pattern normally ceased within 15 min after the end of RPCH superfusion. However, when proctolin was applied within a few minutes of that time, it was likewise able to induce cardiac sac activity. Similarly, proctolin applied together with subthreshold RPCH induced cardiac sac bursting. The amplitude of the excitatory postsynaptic potentials from the IV neurons to the cardiac sac dilator neuron CD2 (1 of the 2 major motor neurons in the cardiac sac system) was potentiated in the presence of both proctolin and RPCH. The potentiation in RPCH was much greater than in proctolin alone. However, the potentiation in proctolin after RPCH was equivalent to that recorded in RPCH alone. Although we do not yet understand the mechanisms for these interactions of the two modulators, this study provides an example of one factor that can determine the "state" of the system that is critical in determining the effect of a modulator that is "state dependent," and it provides evidence for yet another level of flexibility in the motor output of this system.J Neurophysiol 1997772e599-610p>7Dickinson, P. S. Hauptman, J. Hetling, J. Mahadevan, A.ihbRCPH modulation of a multi-oscillator network: effects on the pyloric network of the spiny lobsterrlAnimal Electrophysiology Female Heart/physiology Invertebrate Hormones/*pharmacology Lobsters/*physiology Male Nerve Net/*drug effects/*physiology Neural Inhibition/physiology Neurons/physiology Oligopeptides/*pharmacology Oscillometry Pylorus/*innervation Reference Values Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Synaptic Transmission/drug effectsThe neuropeptide red pigment concentrating hormone (RPCH), which we have previously shown to activate the cardiac sac motor pattern and lead to a conjoint gastric mill-cardiac sac pattern in the spiny lobster Panulirus, also activates and modulates the pyloric pattern. Like the activity of gastric mill neurons in RPCH, the pattern of activity in the pyloric neurons is considerably more complex than that seen in control saline. This reflects the influence of the cardiac sac motor pattern, and particularly the upstream inferior ventricular (IV) neurons, on many of the pyloric neurons. RPCH intensifies this interaction by increasing the strength of the synaptic connections between the IV neurons and their targets in the stomatogastric ganglion. At the same time, RPCH enhances postinhibitory rebound in the lateral pyloric (LP) neuron. Taken together, these factors largely explain the complex pyloric pattern recorded in RPCH in Panulirus.c'`YDepartment of Biology, Bowdoin College, Brunswick, Maine 04011, USA. pdickins@bowdoin.edun11287466J Neurophysiol 2001854 1424-35.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11287466 http://www.jn.physiology.org/cgi/content/full/85/4/1424 http://www.jn.physiology.org/cgi/content/abstract/85/4/1424m Dindle, H. Caldwell, R.L. 1978b\Ecology and morphology of feeding and agonistic behavior in mudflat stomatopods (Squillidae) Biol Bull 155134-149ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10477125 ZTDircksen, H. Skiebe, P. Abel, B. Agricola, H. Buchner, K. Muren, J. E. Nassel, D. R.Structure, distribution, and biological activity of novel members of the allatostatin family in the crayfish Orconectes limosushAmino Acid Sequence Animal Chromatography, High Pressure Liquid Cockroaches/drug effects Crayfish/*chemistry Immunoenzyme Techniques Immunohistochemistry Muscles/drug effects/physiology Neuropeptides/chemistry/*metabolism/pharmacology Support, Non-U.S. Gov't<6In the central and peripheral nervous system of the crayfish, Orconectes limosus, neuropeptides immunoreactive to an antiserum against allatostatin I (= Dipstatin 7) of the cockroach Diploptera punctata have been detected by immunocytochemistry and a sensitive enzyme immunoassay. Abundant immunoreactivity occurs throughout the central nervous system in distinct interneurons and neurosecretory cells. The latter have terminals in well-known neurohemal organs, such as the sinus gland, the pericardial organs, and the perineural sheath of the ventral nerve cord. Nervous tissue extracts were separated by reverse-phase high-performance liquid chromatography and fractions were monitored in the enzyme immunoassay. Three of several immunopositive fractions have been purified and identified by mass spectroscopy and microsequencing as AGPYAFGL-NH2, SAGPYAFGL-NH2, and PRVYGFGL-NH2. The first peptide is identical to carcinustatin 8 previously identified in the crab Carcinus maenas. The others are novel and are designated orcostatin I and orcostatin II, respectively. All three peptides exert dramatic inhibitory effects on contractions of the crayfish hindgut. Carcinustatin 8 also inhibits induced contractions of the cockroach hindgut. Furthermore, this peptide reduces the cycle frequency of the pyloric rhythms generated by the stomatogastric nervous system of two decapod species in vitro. These crayfish allatostatin-like peptides are the first native crustacean peptides with demonstrated inhibitory actions on hindgut muscles and the pyloric rhythm of the stomatogastric ganglion.'TNInstitute of Zoophysiology, University of Bonn, Germany. Dircksen@uni- bonn.de10477125 1999Peptides206695-712 Using Smart Source Parsing .*#Faumont, S. Simmers, J. Meyrand, P.MnhActivation of a lobster motor rhythm-generating network by disinhibition of permissive modulatory inputsAction Potentials/physiology Animal Ganglia, Invertebrate/cytology/*physiology In Vitro Lobsters Motor Neurons/*physiology Nerve Net/*physiology *Periodicity Support, Non-U.S. Gov'to.'Rhythm generation by the gastric motor network in the stomatogastric ganglion (STG) of the lobster Homarus gammarus is controlled by modulatory projection neurons from rostral commissural ganglia (CoGs); blocking action potential conduction in these inputs to the STG of a stomatogastric nervous system in vitro rapidly renders the gastric network silent. However, exposure of the CoGs to low Ca2+ saline to block chemical synapses activates a spontaneously silent gastric network or enhances an ongoing gastric rhythm. A similar permissive effect was observed when picrotoxin was also superfused on these ganglia. We conclude that in the CoGs continuous synaptic inhibition is exerted on modulatory projection neuron(s) and that release from this inhibition allows strong activation of the gastric network.'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I et Centre National de la Recherche Scientifique Unite Mixte de Recherche 5816, F-33120 Arcachon, France.9819280http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9819280 http://jn.physiology.org/cgi/content/full/80/5/2776J Neurophysiol 19988052776-80.$Felgenhauer, B.E. Abele, L.G.  1985PIFeeding structures of 2 Atyid shrimps with comments on Caridean phylogeny J Crust Biol53397-419$Felgenhauer, B.E. Abele, L.G.  19894.Evolution of the foregut in the lower Decapoda @9Felgenhauer, B.E. Watling, L. Thistle, A.B. Balkema, A.A.TMCrustacean Issues: Functional Morphology of Feeding and Grooming in Crustacea  Rotterdam  Brookfield6205-219XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9733079<5Fenelon, V. S. Casasnovas, B. Faumont, S. Meyrand, P.e}Ontogenetic alteration in peptidergic expression within a stable neuronal population in lobster stomatogastric nervous systemnAnimal Antibodies Antimetabolites Bromodeoxyuridine Cell Count Ganglia, Invertebrate/chemistry/cytology/growth & development Larva/growth & development/metabolism Lobsters/*physiology Nervous System/cytology/growth & development/metabolism Neuronal Plasticity/physiology Neurons/chemistry/cytology/*metabolism Neurotransmitters/metabolism Oligopeptides/analysis/immunology/*metabolism Support, Non-U.S. Gov't("In the adult lobster, Homarus gammarus, the stomatogastric ganglion (STG) contains two well-defined motor pattern generating networks that receive numerous modulatory peptidergic inputs from anterior ganglia. We are studying the appearance of extrinsic peptidergic inputs to these networks during ontogenesis. Neuron counts indicate that as early as 20% of development (E20) the STG neuronal population is quantitatively established. By using immunocytochemical detection of 5-bromo-2'- deoxyuridine incorporation, we found no immunopositive cells in the STG by E70. We concluded that the STG neuronal population remains quantitatively stable from mid-embryonic life until adulthood. We then investigated the ontogeny of FLRFamide- and proctolin-like peptides in the stomatogastric nervous system, from their first appearance until adulthood by using whole mount immunocytochemistry. Numerous FLRFamide- like-immunoreactive STG neuropilar ramifications were observable as early as E45 and remain thereafter. From E50 to the first larval stage, one to three STG somata stained, while somatic staining was not observed in larval stage II and subsequent stages. From E50 and thereafter, the STG neuropilar area was immunopositive for proctolin. One to two proctolinergic somata were detected in the STG of the three larval stages but were not seen in embryos, the post-larval stage or in adults. Thus, peptidergic inputs to the STG are present from mid- embryonic life. Moreover, whereas in the adult, STG neurons only contain glutamate or acetylcholine, some neurons transiently express peptidergic phenotypes during development. Although this system expresses an ontogenetic peptidergic plasticity, the STG neurons produce a single stable embryonic-larval motor output (Casasnovas and Meyrand [1995] J. Neurosci. 15:5703-5718).'zLaboratoire de Neurobiologie des Reseaux, CNRS et Universite de Bordeaux I, Arcachon, France. v.fenelon@lnpc.u-bordeaux.fr9733079 J Comp Neurol 1998 3993289-305.99142388e6i 1998 Decs0*Development of rhythmic pattern generators 705-9g|uIn contrast to the wealth of knowledge about the organizational rules of adult central pattern generators, far less is known about how these networks are assembled during development. The basic architecture for adult central pattern generators appears early in development but different generators may follow completely different developmental pathways to reach maturity. Recent evidence suggests that neuromodulatory inputs, in addition to their short-term adaptive control of central pattern generator activity, play a crucial role in both the final developmental tuning and the long-term maintenance of adult network function.o'Laboratoire de Neurobiologie des Reseaux, Universite Bordeaux I and CNRS UMR 5816, Place du Dr Peyneau, F-33120 Arcachon, France.n<5Fenelon, V. S. Casasnovas, B. Simmers, J. Meyrand, P.o@:99116054 0959-4388 Journal Article Review Review, TutorialCurr Opin Neurobiol Aging/physiology Animal Brain/embryology/*physiology Embryo/physiology Motor Activity/physiology Neural Pathways/physiology *Periodicity Support, Non-U.S. Gov'tjdhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9914238 d 84188169& Edwards, D. H., Jr. Mulloney, B.f`Compartmental models of electrotonic structure and synaptic integration in an identified neuroneAction Potentials Animal *Cell Compartmentation Computers Dendrites/physiology Electric Conductivity Electric Stimulation Lobsters *Models, Neurological Motor Neurons/*physiology Neural Inhibition Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiologymA three-compartment model of the electrotonic structure of an identified motoneurone, the median gastric (m.g.) neurone of the stomatogastric ganglion of the spiny lobster (Panulirus interruptus) was constructed, based on the passive response of the cell to a step of injected current. While its structure is only remotely related to that of the cell, the model is able to predict the passive response of the cell to any wave form of injected current. The shape of the m.g. neurone provided the basis for the development of a multicompartment model of the cell from the simple compartment model. Unlike the three- compartment model, the multicompartment model has a structure that corresponds closely to that of the cell while it retains the ability to predict the passive response of the cell to any wave form of injected current. The multicompartment model was used to analyse the electrotonic structure and synaptic integration of the cell. The axon acts as a current sink, causing steady-state voltage attenuation between the tips of different dendrites and the integrating segment to range between 26 and 89%. Steady-state voltage attenuation in the distal direction is 2% or less. Synaptic inhibition of m.g. by Interneurone 1 was simulated with simultaneously activated conductance- increase synapses located on all dendritic end-compartments of the model. Inhibitory post-synaptic potential (i.p.s.p.) wave forms recorded in the cell soma were duplicated in the soma compartment when the synaptic conductance change in each of the twenty-eight end- compartments was set equal to 5 nS for 8 ms. I.p.s.p. wave forms in dendritic end-compartments were 30% larger than the soma compartment i.p.s.p., while i.p.s.p.s in the integrating segment compartment were intermediate in size. Charge from a 92 mV, 1 ms action potential in the model axon was passively conducted from axonal compartments to the soma compartment of the model, where it reproduced the attenuated, broadened voltage wave forms of action potentials recorded in the cell soma. Passive spread of charge from an axonal action potentials to terminal dendritic compartments evoked potentials there that were 30% larger and faster than the corresponding soma compartment potential.J Physiol (Lond) 1984 348 89-11383111097Eisen, J. S. Marder, E.bMechanisms underlying pattern generation in lobster stomatogastric ganglion as determined by selective inactivation of identified neurons. III. Synaptic connections of electrically coupled pyloric neuronsAnimal Electrophysiology Evoked Potentials Ganglia/*physiology Interneurons/physiology Light Lobsters/*physiology Motor Neurons/physiology Periodicity Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology Synaptic Transmissionxr1. The pyloric dilator (PD) and anterior burster (AB) neurons in the pyloric system of the lobster stomatogastric ganglion are electrically coupled and synchronously active. We have used the lucifer yellow photoinactivation technique to separate the connections made by the PD motor neurons from those made by the AB interneuron. 2. Photoinactivation of either the two PD neurons or the single AB neuron allowed us to separate the compound inhibitory postsynaptic potentials (IPSPs) in the lateral pyloric (LP) and pyloric (PY) motor neurons resulting from synchronous PD and AB activity into AB-evoked and PD- evoked components. These IPSPs have different time courses, reversal potentials, ion selectivities, and pharmacological properties. 3. Photoinactivation and membrane-potential manipulations indicated that a readily observable IPSP recorded in the AB neuron and correlated with action potentials in the LP neuron is actually an electrotonic potential due to an LP-evoked IPSP in the PD neurons. 4. Selective inactivation of either the two PD neurons or the AB neuron revealed that the IPSP recorded in the ventricular dilator (VD) motor neuron is due solely to AB-released transmitter. 5. The electrical coupling potentials measurable between the AB, PD, and VD neuron somata are due to direct electrical coupling between all of these neurons. 6. Circuit analysis and transmitter identification may be complicated by electrical coupling. We suggest that the presence of electrical coupling between nonidentical neurons may provide a new mechanism that allows changes in synaptic characteristics among neurons within a "hard- wired" circuit.J Neurophysiol 1982486 1392-141584241938Eisen, J. S. Marder, E. HAA mechanism for production of phase shifts in a pattern generatormAnimal Biomechanics Interneurons/physiology Lobsters Motor Neurons/physiology Neurons/physiology Neurotransmitters/physiology Pyloric Antrum/*innervation Reaction Time Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/physiologye During motor activity of the pyloric system of the lobster stomatogastric ganglion, there are rhythmic alternations between activity in the pyloric dilator (PD) and pyloric (PY) motor neurons. We studied the phase relations between PD motor neuron activity and PY motor neuron activity in preparations cycling at a wide range of frequencies and after altering the activity of the PD neurons. The PY neurons fall into two classes, early (PE) and late (PL) (21), distinguished by the different phases in the pyloric cycle at which they fire. The phase at which PE neurons fired and the phase at which PL neurons fired was independent of pyloric cycle frequency over a range of frequencies from 0.5 to 2.25 Hz. The anterior burster (AB) interneuron is electrically coupled to the PD motor neurons. Together the AB and PD neurons form the pacemaker for the pyloric system. Synchronous depolarization of the AB and PD neurons evokes a complex inhibitory post-synaptic potential (IPSP) in PY neurons. This IPSP has two components: an early, AB neuron-derived component and a late, PD neuron-derived component. Deletion of the PD neurons from the pyloric circuit by photoinactivation removed the PD-evoked component of the pacemaker-evoked IPSP. This resulted in a decrease in the duration of the IPSP evoked by pacemaker depolarization and a significant advance in the firing phase of PY neurons. Bath application of dopamine was used to hyperpolarize and inhibit the PD neurons (30), causing them to release less neurotransmitter. As a consequence, the duration of the IPSP evoked by pacemaker depolarization was decreased and the firing phase of the PY neurons was significantly advanced. Stimulation of the inferior ventricular nerve (IVN) produces a slow excitation of the PD neurons (30), causing them to release more neurotransmitter. Consequently, the duration of the IPSP evoked by pacemaker depolarization was increased and the firing phase of the PY neurons was significantly retarded for several cycles of pyloric activity following IVN stimulation. Thus, modulation of the strength of PD-evoked inhibition in PY neurons is responsible for altering the firing phase of the PY neurons with respect to the pyloric pacemaker. We suggest that frequency of the pyloric output and the phase relations of the elements within the pyloric cycle can be regulated independently. The potential implications of these data for modulation of synaptic efficacy in other preparations are discussed.J Neurophysiol 19845161375-93  96150913$Elson, R. C. Selverston, A. I.ztSlow and fast synaptic inhibition evoked by pattern-generating neurons of the gastric mill network in spiny lobstershaAction Potentials/physiology Animal Chlorides/pharmacology Evoked Potentials/drug effects/physiology Lobsters/*physiology Neural Inhibition/drug effects/*physiology Neurons/drug effects/*physiology Picrotoxin/pharmacology Potassium/pharmacology Pylorus/*innervation Support, U.S. Gov't, P.H.S. Synaptic Transmission/drug effects/*physiology Time Factorso Z T1. In this paper we begin an assessment of the role of synaptic properties, especially synaptic time course, in the function of the central pattern generator circuit (CPG) that controls rhythmic movements of the gastric mill in the foregut of spiny lobster (Panulirus interruptus). 2. The majority of neurons in the gastric CPG are motor neurons (MNs) that innervate striated muscles of the gastric mill but that also make electrical and inhibitory chemical interconnections within the neuropil of the stomatogastric ganglion. We studied the ionic dependence, pharmacology, and time course of inhibitory postsynaptic potentials (IPSPs) evoked by two such MNs, the dorsal gastric (DG) and lateral gastric (LG), in their central synaptic partners. In the periphery, LG and DG are thought to release glutamate. 3. LG and DG evoke two types of IPSPs in follower neurons. The first, fast type of IPSP rises rapidly (the graded component within 100-300 ms, the spike-mediated components within a few tens of ms), is mediated by increased chloride and potassium conductances, and is blocked by or = 10 microM picrotoxin (PTX). These fast IPSPs closely resemble the glutamatergic IPSPs described in the pyloric circuit of the same ganglion. 4. The second, slow type of IPSP has a long rise time (1-2 s), is mediated by increased conductance to potassium (with little or no involvement of chloride), and is not blocked by 10 microM PTX, 5 mM tetraethylammonium chloride, or 0.1 mM scopolamine. These properties distinguish slow IPSPs from the forms of glutamatergic and cholinergic inhibition that have been described in the pyloric circuit. 5. Fast inhibition occurs alone at connections from DG and LG to power stroke MNs (median gastric and gastric mill). Slow inhibition occurs in parallel with fast inhibition (producing dual-component responses) at connections from LG to return stroke neurons [lateral posterior gastric MNs, (LPGs) and interneuron 1]. DG seems to evoke only a slow IPSP in LPGs. 6. The transmitter mediating the fast IPSPs is likely to be glutamate. We discuss possible mechanisms for the slow IPSP but have no evidence at present concerning the transmitter(s) involved. Slow inhibition is likely to be an important synaptic "building block" in the gastric CPG; it is "tuned" to the duration of gastric bursts and may contribute to the long cycle period of gastric rhythms.J Neurophysiol 1995745 1996-201197368838$Elson, R. C. Selverston, A. I.rkEvidence for a persistent Na+ conductance in neurons of the gastric mill rhythm generator of spiny lobsterscAnimal Lobsters/*physiology Membrane Potentials/drug effects Neural Conduction Neurons/*physiology Periodicity Sodium/*physiology Stomach/innervation Support, U.S. Gov't, P.H.S. Tetraethylammonium Compounds/pharmacology Tetrodotoxin/pharmacologytEvidence for a persistent Na+ conductance was obtained in identified motor neurons of the gastric mill network in the stomatogastric ganglion of the spiny lobster Panulirus interruptus. The cells studied were the lateral gastric and lateral posterior gastric motor neurons, which in vivo control chewing movements of the lateral teeth of the gastric mill. We examined basic cellular properties in the quiescent network of the isolated stomatogastric ganglion. In current-clamp recordings, we found two types of evidence for a persistent Na+ conductance. First, tetrodotoxin-sensitive inward rectification occurred during depolarization from rest to spike threshold. Second, 5 mmol l-1 tetraethylammonium (a K+ channel blocker) induced plateau potentials that persisted in the presence of Mn2+ or a low [Ca2+]0 but were blocked by a low [Na+]0 or 100 nmol l-1 tetrodotoxin. The plateau potentials could drive trains of fast spikes in the motor axon and strong transmitter release at central output synapses within the ganglion. This conductance probably corresponds to the persistent Na+ current, INaP, described in cultured stomatogastric neurons and in neurons from several other preparations. During normal neuronal activity, it may contribute to the prolonged plateau depolarizations and long spike trains typical of motor neuronal activity during gastric rhythm generation. Persistent inward currents of this type are likely to be important in neurons that must fire prolonged bursts in cycle after cycle of rhythmical activity. J Exp Biol 1997 200i Pt 12n1795-807RLElson, R. C. Huerta, R. Abarbanel, H. D. Rabinovich, M. I. Selverston, A. I.^WDynamic control of irregular bursting in an identified neuron of an oscillatory circuit Animal Biological Clocks/physiology Digestive System/innervation Ganglia, Invertebrate/*physiology In Vitro Lobsters Membrane Potentials/physiology Neurons/*physiology Oscillometry Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiologyIn the oscillatory circuits known as central pattern generators (CPGs), most synaptic connections are inhibitory. We have assessed the effects of inhibitory synaptic input on the dynamic behavior of a component neuron of the pyloric CPG in the lobster stomatogastric ganglion. Experimental perturbations were applied to the single, lateral pyloric neuron (LP), and the resulting voltage time series were analyzed using an entropy measure obtained from power spectra. When isolated from phasic inhibitory input, LP generates irregular spiking-bursting activity. Each burst begins in a relatively stereotyped manner but then evolves with exponentially increasing variability. Periodic, depolarizing current pulses are poor regulators of this activity, whereas hyperpolarizing pulses exert a strong, frequency-dependent regularizing action. Rhythmic inhibitory inputs from presynaptic pacemaker neurons also regularize the bursting. These inputs 1) reset LP to a similar state at each cycle, 2) extend and further stabilize the initial, quasi-stable phase of its bursts, and 3) at sufficiently high frequencies terminate ongoing bursts before they become unstable. The dynamic time frame for stabilization overlaps the normal frequency range of oscillations of the pyloric CPG. Thus, in this oscillatory circuit, the interaction of rhythmic inhibitory input with intrinsic burst properties affects not only the phasing, but also the dynamic stability of neural activity.'|Department of Biology, Scripps Institution of Oceanography, University of California, San Diego, California 92093-0402, USA.10400940http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10400940 http://www.jn.org/cgi/content/full/82/1/115 http://www.jn.org/cgi/content/abstract/82/1/115J Neurophysiol 1999821115-22.r Dando1974 Dando1974 Dando1974 Dando1977 Davis1983"de Vente2001 Deitmer1993- DeKlotz2003 Dever2004 Dever2004DiCaprio2004% Dick20000} Dickinson1981 Dickinson1981 Dickinson1981| Dickinson1983 Dickinson1983~ Dickinson1988 Dickinson1988t Dickinson1989x Dickinson1989z Dickinson1990{ Dickinson1992y Dickinson1993u Dickinson1995v Dickinson1997w Dickinson2001 Dickinson2001W Dietel1999 Dindle1978Dircksen1999% Doshi1997Y Dreger2002X Dreger20034 Dybek2001 Edwards1984N Edwards2003 Edwards2004 Eigg1989? Eisen1981 Eisen1982' Eisen1984 Eisen1984u Eisen1984v Eisen19845 Eitner1997 El Manira1997 Elson1992 Elson1994 Elson1995 Elson1997& Elson1998 Elson1999 Elson2000B Elson2000 Elson2001 Elson2001 Elson2002 Epstein19908 Epstein1992 Epstein1992m Epstein1993Q Epstein1999 Evans1993Y Evers2002 Ewald1987 Ewer19868 Factor1981 Factor1982 Factor1989v Fairfield1997 Falcke2000% Farnham1997 Faumont1998 Faumont1998 Faumont2000G Felder1989H Felder1990 Felgenhauer1985 Felgenhauer1986 Felgenhauer1989 Fenelon1998 Fenelon1998 Fenelon1999# Fenelon19993 Fenelon19994 Fenelon2001 Fenelon2001 Fenelon2004Fickbohm1987' Flamm1984 Flamm1986 Flamm1986 Flamm1986 Flamm1987 Flamm1987 Flamm1989 Flamm1992 Fleischer1981 French2000 French2002 French2004I Friedi19911 Friend1976 Friesen1986 Frost1996Z Ganeshina2000 Garzino1992 Garzino1994 Gassie19797 Gassie19878 Gassie19939k Geffard1984E Geffard1987 Gibson1977 Gisselmann2003 Glasser1976 Glowik1997 Goaillard2004Godleski1999 Gola1981Goldberg1988 Goldman2001 Goldman2002 Golomb1993 Golowasch1986 Golowasch1989 Golowasch1990 Golowasch19918 Golowasch1992 Golowasch1992 Golowasch1992 Golowasch1992 Golowasch1992 Golowasch1993m Golowasch1993q Golowasch1996 Golowasch1997B Golowasch1998 Golowasch1999 Golowasch1999 Golowasch1999w Golowasch1999h Golowasch2000 Golowasch2001 Golowasch2002I Golowasch2003 Gossard1997 Govind1975 Govind19766 Govind1977 Govind1978 Govind1987 Govind1993E Govind20002# Goy1996Graubard1978Graubard1979Graubard1980Graubard1983Graubard1985>Graubard19878Graubard1987Graubard1987Graubard1988Graubard1989Graubard1991Graubard1992Graubard1993Graubard1995KGraubard19959#Graubard1996MGraubard1997Graubard1998!Graubard1998Graubard2000"Graubard2001NGraubard2003Graubard2003Graubard20040 Greenberg2005Griffith1998Grossman1983 Guckenheimer1993 Guckenheimer1993 Guckenheimer19959 Guckenheimer19959 Guckenheimer1997 Guckenheimer1997 Guckenheimer2003 Gueron1993r Gueron1993r Gueron1995r Gueron19959Gutovitz2001 Hall19901 Hall19911O Hall19941 Harness2002'Harris-Warrick1984Harris-Warrick1986Harris-Warrick1986Harris-Warrick1986Harris-Warrick1987Harris-Warrick1987Harris-Warrick1987Harris-Warrick1988Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1991Harris-Warrick1991Harris-Warrick1991Harris-Warrick1992Harris-Warrick1992Harris-Warrick1992 Harris-Warrick1992!Harris-Warrick1992Harris-Warrick1992Harris-Warrick1993Harris-Warrick1993Harris-Warrick1993Harris-Warrick1993Harris-Warrick1994Harris-Warrick1994Harris-Warrick1994Harris-Warrick1994Harris-Warrick1995Harris-Warrick1995Harris-Warrick1995Harris-Warrick1995Harris-Warrick1995Harris-Warrick1996Harris-Warrick1996 Fenelon2001Fickbohm1987' Flamm1984 Flamm1986 Flamm1986 Flamm1986 Flamm1987 Flamm1987 Flamm1989 Flamm1992 Fleischer1981 French2000̚ French2002̛ French2004I Friedi19911 Friend1976̝ Friesen1986 Frost1996 Garzino1992 Garzino1994 Gassie19797 Gassie19878 Gassie19939k Geffard1984E Geffard1987 Gibson1977̠ Glasser1976 Glowik1997̢ Gola1981̣Goldberg1988̤ Goldman2001 Goldman2002 Golomb1993 Golowasch1986 Golowasch1990 Golowasch19918 Golowasch1992 Golowasch1992 Golowasch1992 Golowasch1992 Golowasch1993m Golowasch1993 Golowasch1997B Golowasch1998 Golowasch1999 Golowasch1999 Golowasch1999 Golowasch2001 Golowasch2002I Golowasch2003 Govind1975 Govind19766 Govind1977 Govind1978̱ Govind1987 Govind1993̲Graubard1978̳Graubard1979̶Graubard1980̷Graubard1983̸Graubard1985>Graubard19878Graubard1987Graubard1988̵Graubard1991Graubard1992Graubard1995KGraubard19959MGraubard1997Graubard1998Graubard2000NGraubard2003̥ Guckenheimer1993̹ Guckenheimer1993 Guckenheimer19959 Guckenheimer19959 Guckenheimer1997̻ Guckenheimer1997̥ Gueron1993r Gueron1993r Gueron1995r Gueron19959Gutovitz2001O Hall19941 Harness2002'Harris-Warrick1984̗Harris-Warrick1986̘Harris-Warrick1986Harris-Warrick1986̖Harris-Warrick1987Harris-Warrick1987Harris-Warrick1987̽Harris-Warrick1988̾Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989Harris-Warrick1989̿Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1990Harris-Warrick1991Harris-Warrick1991Harris-Warrick1991Harris-Warrick1992Harris-Warrick1992Harris-Warrick1992 Harris-Warrick1992!Harris-Warrick1992̹Harris-Warrick1993Harris-Warrick1993Harris-Warrick1993Harris-Warrick1993Harris-Warrick1994Harris-Warrick1994Harris-Warrick1994Harris-Warrick1995Harris-Warrick1995Harris-Warrick1995Harris-Warrick1996Harris-Warrick1996 *: <12205138883 2002 SephbInhibitory synchronization of bursting in biological neurons: dependence on synaptic time constant1166-76Using the dynamic clamp technique, we investigated the effects of varying the time constant of mutual synaptic inhibition on the synchronization of bursting biological neurons. For this purpose, we constructed artificial half-center circuits by inserting simulated reciprocal inhibitory synapses between identified neurons of the pyloric circuit in the lobster stomatogastric ganglion. With natural synaptic interactions blocked (but modulatory inputs retained), these neurons generated independent, repetitive bursts of spikes with cycle period durations of approximately 1 s. After coupling the neurons with simulated reciprocal inhibition, we selectively varied the time constant governing the rate of synaptic activation and deactivation. At time constants 400 ms), bursts became phase-locked in a fully overlapping pattern with little or no phase lag and a shorter period. During the in-phase bursting, the higher-frequency spiking activity was not synchronized. If the circuit lacked a robust periodic burster, increasing the time constant evoked a sharp transition from out-of-phase oscillations to in-phase oscillations with associated intermittent phase-jumping. When a coupled periodic burster neuron was present (on one side of the half-center circuit), the transition was more gradual. We conclude that the magnitude and stability of phase differences between mutually inhibitory neurons varies with the ratio of burst cycle period duration to synaptic time constant and that cellular bursting (whether periodic or irregular) can adopt in-phase coordination when inhibitory synaptic currents are sufficiently slow.'zInstitute for Nonlinear Science, University of California San Diego, La Jolla, California 92093-0402, USA. relson@ucsd.eduHAElson, R. C. Selverston, A. I. Abarbanel, H. D. Rabinovich, M. I.("22194507 0022-3077 Journal ArticleJ NeurophysiolZTAction Potentials/physiology Animal Biological Clocks/physiology Computer Simulation Electrophysiology Ganglia/physiology Lobsters Models, Neurological Neural Inhibition/*physiology Neurons/*physiology Oscillometry Pylorus/innervation Reaction Time/physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiologylehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=1220513890291044 Epstein, I. R. Marder, E.u81Multiple modes of a conditional neural oscillatorHAction Potentials Calcium/physiology *Models, Neurological Neurons/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.We present a model for a conditional bursting neuron consisting of five conductances: Hodgkin-Huxley type time- and voltage-dependent Na+ and K+ conductances, a calcium activated voltage-dependent K+ conductance, a calcium-inhibited time- and voltage-dependent Ca++ conductance, and a leakage Cl- conductance. With an initial set of parameters (version S), the model shows a hyperpolarized steady-state membrane potential at which the neuron is silent. Increasing gNa and decreasing gCl, where gi is the maximal conductance for species i, produces bursts of action potentials (Burster N). Alternatively, an increase in gCa produces a different bursting state (Burster C). The two bursting states differ in the periods and amplitudes of their bursting pacemaker potentials. They show different steady-state I-V curves under simulated voltage-clamp conditions; in simulations that mimic a steady-state I-V curve taken under experimental conditions only Burster N shows a negative slope resistance region. Model C continues to burst in the presence of TTX, while bursting in Model N is suppressed in TTX. Hybrid models show a smooth transition between the two states. 1990 Biol Cybern631 25-34 Using Smart Source ParsingEwald, D.A. Barker, D.L. 1987Dopaminergic modulation of the lobster pyloric pacemaker potential is enhanced by concurrent inhibition of cyclic nucleotide phosphodiesterase "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-Verlag301-303 Factor, J.R. 1981rDevelopment and metamorphosis of the digestiv system of larval lobster, Homarus americanus (Decapoda: Nephropidae)HZ J Morphol 169225-242 Factor, J.R. 1982qDevelpment and metmorphosis of the feeding apparatus of the stone crab, Menippe mercenaria (Brachyura Xanthindae)AHZ J Morphol 1723299-312 Factor, J.R. 1989B;Development of the feeding apparatus in decapod crustaceans @9Felgenhauer, B.E. Watling, L. Thistle, A.B. Balkema, A.A.TMCrustacean Issues: Functional Morphology of Feeding and Grooming in Crustacea  Rotterdam  Brookfield6185-203ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10879435)^WFalcke, M. Huerta, R. Rabinovich, M. I. Abarbanel, H. D. Elson, R. C. Selverston, A. I. f`Modeling observed chaotic oscillations in bursting neurons: the role of calcium dynamics and IP3NGAction Potentials Animal Calcium/*metabolism Calcium Channels/metabolism Human Inositol 1,4,5-Trisphosphate/*metabolism Lobsters *Models, Biological Neurons/metabolism/*physiology Pylorus/innervation/metabolism/physiology Receptors, Cytoplasmic and Nuclear/metabolism Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Chaotic bursting has been recorded in synaptically isolated neurons of the pyloric central pattern generating (CPG) circuit in the lobster stomatogastric ganglion. Conductance-based models of pyloric neurons typically fail to reproduce the observed irregular behavior in either voltage time series or state-space trajectories. Recent suggestions of Chay [Biol Cybern 75: 419-431] indicate that chaotic bursting patterns can be generated by model neurons that couple membrane currents to the nonlinear dynamics of intracellular calcium storage and release. Accordingly, we have built a two-compartment model of a pyloric CPG neuron incorporating previously described membrane conductances together with intracellular Ca2+ dynamics involving the endoplasmic reticulum and the inositol 1,4,5-trisphosphate receptor IP3R. As judged by qualitative inspection and quantitative, nonlinear analysis, the irregular voltage oscillations of the model neuron resemble those seen in the biological neurons. Chaotic bursting arises from the interaction of fast membrane voltage dynamics with slower intracellular Ca2+ dynamics and, hence, depends on the concentration of IP3. Despite the presence of 12 independent dynamical variables, the model neuron bursts chaotically in a subspace characterized by 3-4 active degrees of freedom. The critical aspect of this model is that chaotic oscillations arise when membrane voltage processes are coupled to another slow dynamic. Here we suggest this slow dynamic to be intracellular Ca2+ handling.'ngMax Planck-Institute for the Physics of Complex Systems, Dresden, Germany. falcke@mpipks-dresden.mpg.def10879435 Biol Cyberna 2000826i517-27.r :onPirenzepine/pharmacologyPlastic EmbeddingPolymerase Chain Reaction Potassium Channel Blockers,'Potassium Channels/*genetics/metabolism$Potassium Channels/*physiology40Potassium Channels/analysis/genetics/*physiology0+Potassium Channels/drug effects/*physiology0*Potassium Channels/drug effects/metabolism,'Potassium Channels/genetics/*metabolism Potassium Channels/metabolism Potassium Channels/physiologyPotassium/*physiologyPotassium/metabolism$!Potassium/metabolism/pharmacologyPotassium/pharmacologyPotassium/physiologyPrecipitin TestsPredictive Value of Tests$!Presynaptic Terminals/*physiology40Presynaptic Terminals/*physiology/ultrastructure(%Presynaptic Terminals/*ultrastructure4/Presynaptic Terminals/metabolism/ultrastructure$ Presynaptic Terminals/physiologyProcaine/pharmacologyProglumide/pharmacology Proprioception/*physiology($Protein Isoforms/genetics/metabolism Protein Kinase C/metabolismPsychomotor Performance("Psychomotor Performance/physiologypurification/*physiology Purkinje Cells/*physiology Pyloric Antrum/*innervation Pyloric Antrum/*physiology Pyloric Antrum/innervationpyloric pattern PylorusPylorus/*innervation$Pylorus/*innervation/physiologyPylorus/*physiology Pylorus/cytology/*innervation Pylorus/cytology/drug effects,'Pylorus/cytology/innervation/physiologyPylorus/drug effects$ Pylorus/drug effects/innervation$Pylorus/drug effects/physiologyPylorus/innervation$Pylorus/innervation/*physiology,)Pylorus/innervation/metabolism/physiology$Pylorus/innervation/physiologyPylorus/physiology Quisqualic Acid/pharmacology RabbitsRadioimmunoassayRats Reaction TimeReaction Time/physiologyReceptors, Cholinergic($Receptors, Cholinergic/*drug effects4.Receptors, Cholinergic/drug effects/physiology0-Receptors, Cytoplasmic and Nuclear/metabolism$Receptors, Dopamine/*metabolismD>Receptors, GABA-B/agonists/antagonists & inhibitors/metabolism@7Voltage clamp analysis of intact stomatogastric neurons&Animal Calcium Channels/drug effects Electrophysiology Ion Channels/drug effects Lobsters/*physiology Neurons/*physiology Pylorus/innervation Stomach/*innervation Support, U.S. Gov't, P.H.S. Tetraethylammonium Compounds/pharmacology Tetrodotoxin/pharmacology 4-Aminopyridine/pharmacology.Two-electrode voltage clamp of intact, identified pyloric neurons of the spiny lobster stomatogastric ganglion reveals two major outward currents. A rapidly inactivating, tetraethylammonium- (TEA) insensitive, 4-aminopyridine- (4AP) sensitive, outward current resembles IA of molluscan neurons; it activates rapidly on depolarizations above rest (e.g. -45 mV), delaying both the axonal- sodium and the neuropil-calcium spikes which escape voltage-clamp control. We infer that A-current is distributed both in a space clamped region (on or near the soma) and in a non-space clamped region with access to the generators for sodium and calcium spikes. A calcium- dependent outward current, IO(Ca), activates rapidly at clamp steps above -25 mV and inactivates at depolarizing holding voltages. Increasing depolarization results in an increase in both IO(Ca) and firing rate but a reduction in the amplitude of the sodium spike current. Blockage of IO(Ca) with Cd2+ causes little change in spike firing pattern. These observations are consistent with IO(Ca) being activated primarily in the soma and nearby regions which are under good control with a soma voltage clamp (and distant from the Na(+)-spike trigger zone). While the lack of space clamp limits resolution of charging transients and tail currents, the identification of the major current subgroups can still be readily accomplished, and inferences about the location and function of currents can be made which would not be possible if the cells were space clamped or truncated. Brain Rest 1991 557e 1-2n 241-5415356180932 2005 FebanhSynaptic depression in conjunction with a-current channels promote phase constancy in a rhythmic network 656-77In many central pattern generators, pairs of neurons maintain an approximately fixed phase despite large changes in the frequency. The mechanisms underlying phase maintenance are not clear. Previous theoretical work suggested that inhibitory synapses that show short-term depression could play a critical role in this respect. In this work we examine how the interaction between synaptic depression and the kinetics of a transient potassium (A-like) current could be advantageous for phase constancy in a rhythmic network. To demonstrate the mechanism in the context of a realistic central pattern generator, we constructed a detailed model of the crustacean pyloric circuit. The frequency of the rhythm was modified by changing the level of a ligand-activated current in one of the pyloric neurons. We examined how the time difference of firing activities between two selected neurons in this circuit is affected by synaptic depression, A-current, and a combination of the two. We tuned the parameters of the model such that with synaptic depression alone, or A-current alone, phase was not maintained between these two neurons. However, when these two components came together, they acted synergistically to maintain the phase across a wide range of cycle periods. This suggests that synaptic depression may be necessary to allow an A-current to delay a postsynaptic neuron in a frequency-dependent manner, such that phase invariance is ensured.r'|Life Sciences Dept., Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, Israel 84105. yairman@bgumail.bgu.ac.il).Greenberg, I. Manor, Y.y 0022-3077 Journal Article J Neurophysiollehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15356180 9407791281Guckenheimer, J. Gueron, S. Harris-Warrick, R. M.a0)Mapping the dynamics of a bursting neuroniAction Potentials Animal Electrophysiology Ganglia, Invertebrate/physiology Ion Channels/metabolism *Models, Neurological Neurons/drug effects/*physiology Potassium Channels/drug effects/metabolism Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. 4-Aminopyridine/pharmacologyThe anterior burster (AB) neuron of the lobster stomatogastric ganglion displays varied rhythmic behavior when treated with neuromodulators and channel-blocking toxins. We introduce a channel-based model for this neuron and show how bifurcation analysis can be used to investigate the response of this model to changes of its parameters. Two dimensional maps of the parameter space of the model were constructed using computational tools based on the theory of nonlinear dynamical systems. Changes in the intrinsic firing and oscillatory properties of the model AB neuron were correlated with the boundaries of Hopf and saddle-node bifurcations on these maps. Complex rhythmic patterns were observed, with a bounded region of the parameter plane producing bursting behavior of the model neuron. Experiments were performed by treating an isolated AB cell with 4-aminopyridine which selectively reduces gA, the conductance of the transient potassium channel. The model accurately predicts the qualitative changes in the neuronal voltage oscillations that are observed over a range of reduction of gA in the neuron. These results demonstrate the efficacy of dynamical systems theory as a means of determining the varied oscillatory behaviors inherent in a channel- based neural model. Further, the maps of bifurcations provide a useful tool for determining how these behaviors depend upon model parameters and comparing the model to a real neuron.("Philos Trans R Soc Lond B Biol Sci 1993 341t 1298 345-59 (!Golowasch, J. Manor, Y. Nadim, F.m82Recognition of slow processes in rhythmic networksAnimal Calcium Signaling/physiology Human Models, Neurological Nerve Net/*physiology Neural Inhibition/physiology Neuronal Plasticity/*physiology *Periodicity Synaptic Transmission/*physiology'TNVolen Center for Complex Systems, Brandeis University, Waltham, MA 02454, USA.10441293http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10441293 http://www.biomednet.com/library/fulltext/TINS.etd00119_01662236_v0022i09_00001466 http://www.biomednet.com/library/abstract/TINS.etd00119_01662236_v0022i09_00001466NTrends Neurosci  1999229n 375-7.<5Golowasch, J. Goldman, M. S. Abbott, L. F. Marder, E. RLFailure of averaging in the construction of a conductance-based neuron modelAction Potentials/physiology Animal Crabs Ganglia, Invertebrate/cytology/physiology *Models, Neurological Neurons/*physiology Potassium/metabolism Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.,%Parameters for models of biological systems are often obtained by averaging over experimental results from a number of different preparations. To explore the validity of this procedure, we studied the behavior of a conductance-based model neuron with five voltage- dependent conductances. We randomly varied the maximal conductance of each of the active currents in the model and identified sets of maximal conductances that generate bursting neurons that fire a single action potential at the peak of a slow membrane potential depolarization. A model constructed using the means of the maximal conductances of this population is not itself a one-spike burster, but rather fires three action potentials per burst. Averaging fails because the maximal conductances of the population of one-spike bursters lie in a highly concave region of parameter space that does not contain its mean. This demonstrates that averages over multiple samples can fail to characterize a system whose behavior depends on interactions involving a number of highly variable components.0'Volen Center for Complex Systems and Department of Biology, Brandeis University, Waltham, MA 02454, USA. golowasch@stg.rutgers.edu11826077J Neurophysiol 2002872 1129-31.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11826077 http://jn.physiology.org/cgi/content/full/87/2/1129 http://jn.physiology.org/cgi/content/abstract/87/2/1129 .'Govind, C.K. Atwood, H.L. Maynard, D.M. 1975piInnervation and neuronmuscular physiology of intrinsic foregut muscles in the blue crab and spiny lobsterJ Comp Physiol96185-204 Govind, C.K. Lingle, C.J. 19872+Neuromuscular organization and pharmacology "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-Verlag 31-48 Animal78244172 Graubard, K.rkSynaptic transmission without action potentials: input-output properties of a nonspiking presynaptic neuronAnimal Lobsters Membrane Potentials Neural Inhibition Neurons/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiology *Synaptic Transmission 1. Input-output properties of the inhibitory synaptic connection between non-spiking neurons (EX1) and gastric mill (GM) neurons were examined in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. Current was injected into and the voltage was recorded during current injection, two independent microelectrodes were used. 2. The EX1-GM synaptic connection is a conductance-increase inhibitory type, with an input-output curve that resembles the curve for the squid giant synapse. There is a threshold level of depolarization for transmitter release from the presynaptic cell. Beyond that threshold, increasing presynaptic depolarization causes increasing postsynaptic hyperpolarization (and inhibition). 3. A long presynaptic current step always causes a postsynaptic response with an initial peak of hyperpolarization followed by a decay to a less hyperpolarized plateau level. The plateau level is maintained, in most cells, for the duration of the presynaptic depolarization even over long periods (30 s). 4. The peak, but not the plateau, part of the postsynaptic response is sensitive to the past history of the synaptic connection. If a large conditioning pulse is applied to the presynaptic cell causing a large postsynaptic hyperpolarization, then the postsynaptic response to a later presynaptic test depolarization will have a reduced peak, leaving the plateau component unchanged.J Neurophysiol 1978414s1014-25p Graubard, K. Calvin, W.H. 1979d]Presynaptic dentrites: Implications of spikeless synaptic transmission and dendritic geometry Schmitt, F.O. Worden, F.G..'The Neurosciences: Fourth Study Program  Cambridge, MA  MIT Press317-331810139590)Graubard, K. Raper, J. A. Hartline, D. K. :4Graded synaptic transmission between spiking neurons$Action Potentials Animal Electrophysiology Ganglia/*physiology Lobsters Membrane Potentials Neural Inhibition Neurons/physiology Neurotransmitters/*secretion Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology *Synaptic Transmission Tetrodotoxin/pharmacologyGraded synaptic transmission occurs between spiking neurons of the lobster stomatogastric ganglion. In addition to eliciting spike-evoked inhibitory potentials in postsynaptic cells, these neurons also release functionally significant amounts of transmitter below the threshold for action potentials. The spikeless postsynaptic potentials grade in amplitude with presynaptic voltage and can be maintained for long periods. Graded synaptic transmission can be modulated by synaptic input to the presynaptic neuron.eProc Natl Acad Sci U S A 1980776i 3733-5 D  Greenberg, I.Greenspan, R.J.Griffith, L. C. Grillner, S.Grossman, R. I.Guckenheimer, J. Gueron, S. Gutovitz, S. Hall, C. Hall, W. M. Hall, Z.H. Hanson, S.J.Harness, P. I.Harris-Warrick, R.Harris-Warrick, R. M.Harris-Warrick, R.M.Hartenstein, V.Hartline, D. K.Hartline, D.K. Hatt, H. Hauptman, J.Heinzel, H. G. Helluy, S. M. Hemple, C.M. Herbert, E. Herman, R.M. Hermann, A. Hetling, J.Hetling, J. R.Hildebrand, J. G. Hinton, D.J. Hirji, R. Hobbs, K. H. Hooper, N.K. Hooper, S. L. Hooper, S.L Hooper, S.L. Hoover, N. J. Hoyle, G. Hucho, F. Huerta, R. Hughes, S. Hurley, L. M. Icely, J.D. Jackel, C. Jacklet, J.Jahromi, S. S.Johannen, K.C.Johnson, B. R. Johnson, B.R. Jones, B. R. Jones, B.R.Jorge-Rivera, J.Jorge-Rivera, J. C.Jorge-Rivera, J.C. Kappen, B.Kater Katz, P. S. Katz, P.S. Kebabian, J. Kehoe, J. Keller, R. Kelley, D. Kelley, W. P. Kelson Kennedy, D.Kennedy, M. B. Kennedy, M.B. Kepler, T. B. Kepler, T.B. Kiehn, O. Kien, J. Kilman, V. Kilman, V. L. Kim, M. Kim, M.T. King, D. G. Kirk, M.D. Kittaka, J. Kjaerulff, O.Kloppenburg, P. Koch, C.Konstant, P. H. Kopell, N. Kordon, C.Kravitz, E. A. Krenz, W. Krenz, W. D. Krenz, W.-D. Kumar, W. Kunze, J.C. Kushner, P.D. Kwan, I.Kyriacou, C.P. Labenia, J. Lange, A. B.Lanning, C. C. Lanning, C.C.Larimer, J. L.Laverack, M. S.Laverack, M.S. Le Feuvre, Y. Le Moal, M. Legeay, A. Leger, C.L. LeMasson, G. Lengvari, I. Levi, R. Levini, M.T. Levini, R. M. Levini, R.M. Li, L. Lin, M. Lingle, C. Lingle, C. J. Lingle, C.J.Lippmann, R.P. Liu, Z.Lnenicka, G. A. LoFaro, T. Lovett, D.L. Lubell, J.K. Lubics, A.Lundquist, C. T. Luther, J. A.MacLean, J. N.Macmillan, D.L. Mahadevan, A. Mamiya, A.Mancillas, J. R. Mandell Manhas, A. S. Mann, K.H. Manor, Y. Mantel, L.H. Marder, E. Marder, Y. E. Marin, L.Masinovsky, B.Massabuau, J. C. Matly, M.Maynard, D. M. Maynard, D.M. Maynard, E.A. Mayrand, P. Mazzoni, P. McCollum, G. McCrohan, C. McKenna, T.M. Mecsas, C. Meier, T. Meiss, D.E. Menzel, R. Mercier, J. Meseke, M. Messai, E. Meunier, C. Meyrand, .M. Meyrand, P.Miall Miller, J. P. Miller, J.P. Miller, W. L. Mira, M. Mitchison Mittmann, B. Miyatani, M. Miyazaki, T. Mizrahi, A.Mocquard, M.F. Moody, J.E.Moriarty, D.J.W. Morris, J. Morris, L. G. Mortin, L. I.Moskowitz, H.S. Moulins, M Moulins, M.Moulins, Maurice Moulins, S. Mulloney, B. Muren, J. E. Nadim, F. Nagy, E. Nagy, F.Nakanishi, S. T. Nakemura, K. Nargeot, R. Nassel, D. R.Nathanson, J.A. Nemoto, T. Nguyen, D. Nicholson Nishida, S. Nold, K. A. Nonnotte, L. Norman, R.S. Norris, B. J. Nott, J.A.Nozdrachev, A. D.Nusbaum, M. P. Nusbaum, M.P. O'Neil, M. O'Neil, M. B. O'Neil, M.B. Ogden, L. Oliva, R. Olivera, B.M. Orchard, I.Orlovsky, G.N. Oshinsky, M. Panchin, Y.Panchin, Y. V. Parker, T.J.Patwardhan, S.S. L N87282572("Harris-Warrick, R. M. Flamm, R. E.F@Multiple mechanisms of bursting in a conditional bursting neuronAnimal Biogenic Amines/*physiology Calcium/physiology Digestive System/innervation Dopamine/physiology Lobsters/*physiology Membrane Potentials/drug effects Nervous System/drug effects/*physiology *Nervous System Physiology Neurons/drug effects/*physiology Octopamine/physiology Serotonin/physiology Sodium/physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tetraethylammonium Compounds/pharmacology Tetrodotoxin/pharmacologyv@:The anterior burster (AB) neuron in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus, is a conditional burster in the pyloric motor circuit. Bath application of the monoamines dopamine, serotonin, and octopamine induces rhythmic bursting pacemaker potentials in a silent, synaptically isolated AB cell. However, each amine produces a unique and characteristic burst shape, resulting from different ionic dependences of the burst mechanisms. Bursting induced by serotonin or octopamine is critically dependent upon sodium entry through tetrodotoxin-sensitive channels; dopamine-induced bursting is not TTX-sensitive. Dopamine-induced bursting is abolished when extracellular calcium is reduced to 25% of normal; serotonin- and octopamine-induced bursts continue in this saline, although they are abolished in salines with calcium reduced to 10% or less of normal. Quantitative differences between the amines are also seen in the tetraethylammonium (TEA) sensitivity of the burst amplitude and in the dependence of the interburst hyperpolarization on extracellular potassium. These experiments demonstrate that there are both quantitative and qualitative differences in the ionic currents underlying every phase of the bursts induced by the 3 amines. Thus, a single neuron can burst via more than one ionic mechanism. J Neurosci 19877x7u2113-28s87300801*$Harris-Warrick, R. M. Johnson, B. R.ZTPotassium channel blockade induces rhythmic activity in a conditional burster neurond]Action Potentials/drug effects Aminopyridines/pharmacology Animal Apamin/pharmacology Calcium/*physiology Digestive System/innervation Ion Channels/drug effects/*physiology Lobsters/*physiology Neurons/drug effects/*physiology Potassium/physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tetraethylammonium Compounds/pharmacology/In the lobster stomatogastric ganglion the Anterior Burster (AB) neuron loses its rhythmic bursting capabilities when isolated from all synaptic input. Here we report that compounds which reduce the current through several different types of potassium channels induce bursting in isolated AB neurons. These results suggest that when quiescent, this neuron has all the conductances necessary to support bursting, but bursting is actively inhibited by tonic potassium conductances.p Brain Rese 1987 416a2l 381-6rHarris-Warrick, R.M. 198881Chemical modulation of central pattern generators ,&Cohen, A.H. Rossignol, S. Grillner, S.*$Neural Control of Rhythmic Movements New York John Wiley & Sonsi285-331y89303527Harris-Warrick, R. M.shbForskolin reduces a transient potassium current in lobster neurons by a cAMP-independent mechanismAnimal Cyclic AMP/*physiology Forskolin/analogs & derivatives/*pharmacology Ganglia/drug effects/metabolism/*physiology Lobsters/*physiology Membrane Potentials/drug effects Potassium Channels/*physiology Support, U.S. Gov't, P.H.S.Forskolin decreases the transient potassium current, IA, in voltage- clamped somata of identified neurons in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. The diterpene reduces the peak outward current and accelerates the rate of inactivation of IA. Forskolin has no detectable effects on two other identifiable potassium currents in these cells, IK(Ca) and IK(V). Three identified stomatogastric neuron types (PD, PY, AB) have marked amounts of IA which are affected by forskolin; three other cell types (LP, IC, VD) have little or no IA, and forskolin has no effect on their outward currents. Bath application of 8-bromo-cAMP, N,N-dibutyryl-cAMP and IBMX do not affect IA. In addition, the forskolin analog, 1,9- dideoxyforskolin, which does not activate adenylate cyclase, mimics forskolin's effects on IA. Thus, the effects of forskolin on IA are not mediated by cAMP elevation. Brain Res 1989 4891 59-66@9Harris-Warrick, R.M. Flamm, R.E. Johnson, B.R. Katz, P.S. 19890*Modulation of neural circuits in crustaceaAm Zool29 1305-1320("Harris-Warrick, R.M. Johnson, B.R. 1989RLMotor pattern networks: Flexible foundations for rhythmic pattern production Carew, T. Kelley, D.0*Perpectives in Neural Systems and Behavior New York  Alan R. Liss 51-71iHarris-Warrick, R.M. 1990BDynamic Biological Networks: The Stomatogastric Nervous System  Cambridge, MA  MIT Press 87-13894169638Harris-Warrick, R. M.0Pattern generationAnimal Behavior, Animal/*physiology Models, Neurological Nerve Net/*physiology Neurons/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.rSignificant advances have been made in understanding the cellular mechanisms for pattern generation in both invertebrate and vertebrate preparations. In a number of preparations, slow neuromodulators have been shown not only to modify network function, but to be intimately involved in development and/or normal function of the neural network and its associated behavior. The mechanisms underlying coordination between multiple pattern-generating networks, including switching of neurons from one network to another, are now being studied. Several new quantitative models of network function have been developed, and modeling is now an important component of research in this field.Curr Opin NeurobiolP 19933a6A 982-8oHarris-Warrick, R.M. 1994TNModulation of small neural networks in the crustacean stomatogastric ganglion "Selverston, A.I. Ascher, P.JCCellular and Molecular Mechanisms Underlying Higher Neural Function New York John Wiley & Sons111-126p Biogenic Amines/*physiology97401429>7Guckenheimer, J. Harris-Warrick, R. Peck, J. Willms, A.<5Bifurcation, bursting, and spike frequency adaptation,Action Potentials/*physiology Adaptation, Physiological Animal Ganglia, Autonomic/physiology Gastrointestinal System/physiology Lobsters/physiology *Neural Networks (Computer) Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.3Many neural systems display adaptive properties that occur on time scales that are slower than the time scales associated with repetitive firing of action potentials or bursting oscillations. Spike frequency adaptation is the name given to processes that reduce the frequency of rhythmic tonic firing of action potentials, sometimes leading to the termination of spiking and the cell becoming quiescent. This article examines these processes mathematically, within the context of singularly perturbed dynamical systems. We place emphasis on the lengths of successive interspike intervals during adaptation. Two different bifurcation mechanisms in singularly perturbed systems that correspond to the termination of firing are distinguished by the rate at which interspike intervals slow near the termination of firing. We compare theoretical predictions to measurement of spike frequency adaptation in a model of the LP cell of the lobster stomatogastric ganglion.J Comput Neurosci 199743 257-77 Guckenheimer, J. Rowat, P. 1997:4Dynamical systems analysis of real neuronal networks >8Stein, P.S.G. Grillner, S. Selverston, A.I. Stuart, D.G.*$Neuron, Networks, and Motor Behavior  Cambridge, MA  MIT Press151-163 XJDGutovitz, S. Birmingham, J. T. Luther, J. A. Simon, D. J. Marder, E.HAGABA enhances transmission at an excitatory glutamatergic synapseeAnimal Baclofen/pharmacology Electric Stimulation Excitatory Postsynaptic Potentials/drug effects/physiology Female GABA Agonists/pharmacology GABA Antagonists/pharmacology Ganglia, Invertebrate Glutamic Acid/*metabolism/pharmacology In Vitro Iontophoresis Lobsters Male Membrane Potentials/drug effects/physiology Motor Neurons/drug effects/metabolism Muscimol/pharmacology Muscles/innervation/physiology Neuromuscular Junction/drug effects/metabolism Patch-Clamp Techniques Picrotoxin/pharmacology Receptors, GABA-B/agonists/antagonists & inhibitors/metabolism Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/drug effects/*metabolism Synaptic Transmission/drug effects/*physiology gamma-Aminobutyric Acid/*metabolism/pharmacology`YGABA mediates both presynaptic and postsynaptic inhibition at many synapses. In contrast, we show that GABA enhances transmission at excitatory synapses between the lateral gastric and medial gastric motor neurons and the gastric mill 6a and 9 (gm6a, gm9) muscles and between the lateral pyloric motor neuron and pyloric 1 (p1) muscles in the stomach of the lobster Homarus americanus. Two-electrode current- clamp or voltage-clamp techniques were used to record from muscle fibers. The innervating nerves were stimulated to evoke excitatory junctional potentials (EJPs) or excitatory junctional currents. Bath application of GABA first decreased the amplitude of evoked EJPs in gm6a and gm9 muscles, but not the p1 muscle, by activating a postjunctional conductance increase that was blocked by picrotoxin. After longer GABA applications (5-15 min), the amplitudes of evoked EJPs increased in all three muscles. This increase persisted in the presence of picrotoxin. beta-(Aminomethyl)-4-chlorobenzenepropanoic acid (baclofen) was an effective agonist for the GABA-evoked enhancement but did not increase the postjunctional conductance. Muscimol activated a rapid postsynaptic conductance but did not enhance the amplitude of the nerve-evoked EJPs. GABA had no effect on iontophoretic responses to glutamate and decreased the coefficient of variation of nerve-evoked EJPs. In the presence or absence of tetrodotoxin, GABA increased the frequency but not the amplitude of miniature endplate potentials. These data suggest that GABA acts presynaptically via a GABA(B)-like receptor to increase the release of neurotransmitter.'haVolen Center and Biology Department, Brandeis University, Waltham, Massachusetts 02454-9110, USA.11487616 J Neurosci 200121165935-43.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11487616 http://www.jneurosci.org/cgi/content/full/21/16/5935 http://www.jneurosci.org/cgi/content/abstract/21/16/5935& Harris-Warrick, R.M. Flamm, R.E. 1986F@Chemical modulation of a small central pattern generator circuit TINS9432-437 fXRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9292972Hartenstein, V.i>7Development of the insect stomatogastric nervous system Animal Enteric Nervous System/*physiology Ganglia, Invertebrate/physiology Insects/*physiology Stomach/*innervation Support, U.S. Gov't, P.H.S.nhbThe stomatogastric nervous system (SNS) forms a network of peripheral ganglia associated with the insect gut. The SNS originates from a neuroepithelial placode which dissolves into a population of migrating neural precursors. The formation of the SNS presents many parallels to the development of the vertebrate peripheral nervous system. Recent studies have started to provide answers for pertinent questions in SNS development, in particular, how the SNS placode is specified, how SNS precursors are released in a reproducible pattern from this placode and how different cell types in the SNS are determined.'piDept of Molecular, Cell and Developmental Biology, University of California, Los Angeles 90095-1606, USA.r9292972sTrends Neurosciv 1997209o 421-7.76096421$Hartline, D. K. Maynard, D. M.RLMotor patterns in the stomatogastric ganglion of the lobster Panulirus argusAnimal Ganglia/*physiology In Vitro Lobsters/*physiology Motor Neurons/*physiology Muscles/physiology Stomach/innervation/physiology/surgery Support, U.S. Gov't, P.H.S. Synaptic Transmission 1. Acitivity patterns arising from the thirty cells of the stomatogastric ganglion of Panulirus argus are described for both a semi-intact preparation and an isolated one. 2. The thirty or so cells can be divided so far into two functional groupings: the gastric mill group, with at least ten motor elements, and the pyloric group with at least fourteen. There is some, but not extensive, interaction between groups. 3. The main gastric mill activity is arranged in two sets of elements, each of which is composed of reciprocating elements innervating antagonistic muscles. Thus alternation in activity between the single LC and the two LG neurones results in alternate closing and opening of the lateral teeth; alternation between the four GM and single CP units results in alternate protraction and retraction of the medial tooth. 4. The two sets are phased to each other in such a way that they cause gastric mill teeth to operate effectively to masticate food. 5. The main pyloric activity is arranged in a three-part cycle with each of three sets of units active in sequence. Activity in two PD and one AB unit is followed by bursts in IC and LP units followed in turn by activity in up to seven PY units. Activity in a single VD neurone is locked to this cycle in a more complex pattern.f J Exp Biol 1975622  405-2080043198Hartline, D. K. lePattern generation in the lobster (Panulirus) stomatogastric ganglion. II. Pyloric network simulationD>Animal Electric Stimulation Ganglia/*physiology Lobsters Membrane Potentials *Models, Neurological Nerve Net/*physiology Nervous System/*physiology *Nervous System Physiology Neurons/*physiology Pylorus/*innervation Stomach/innervation Support, U.S. Gov't, P.H.S. Synapses/physiology Synaptic Transmission Time Factors 1. Results from the companion paper were incorporated into a physiologically realistic computer model of the three principal cell types (PD/AB, LP, PY) of the pyloric network in the stomatogastric ganglion. Parameters for the model were mostly calculated (sometimes estimated) from experimental data rather than fitting the model to observed output patterns. 2. The initial run was successful in predicting several features of the pyloric pattern: the observed gap between PD and LP bursts, the appropriate sequence of the activity periods (PD, LP, PY), and a substantial PY burst not properly simulated by an earlier model. 3. The major discrepancy between model and observed patterns was the too-early occurrence of the PY burst, which resulted in a much shortened LP burst. Motivated by this discrepancy, additional investigations were made of PY properties. A hyperpolarization-enabled depolarization-activated hyperpolarizing conductance change was discovered which may make an important contribution to the late phase of PY activity in the normal burst cycle. Addition of this effect to the model brought its predictions more in line with observed patterns. 4. Other discrepancies between model and observation were instructive and are discussed. The findings force a substantial revision in previously held ideas on pattern production in the pyloric system. More weight must be given to functional properties of individual neurons and less to properties arising purely from network interactions. This shift in emphasis may be necessary in more complicated systems as well. 5. An example has been provided of the value quantitative modeling can be to network physiology. Only through rigorous quantitative testing can qualitative theories of how the nervous system operates be substantiated. Biol Cybern 1979334 223-36 IlrGastrointestinal Motility,'Gastrointestinal Motility/*drug effects(%Gastrointestinal Motility/*physiology82Gastrointestinal Motility/drug effects/*physiology($Gastrointestinal Motility/physiology40Gastrointestinal System/*drug effects/physiology($Gastrointestinal System/*innervation(#Gastrointestinal System/*physiology(#Gastrointestinal System/innervation4/Gastrointestinal System/innervation/*physiology4.Gastrointestinal System/innervation/physiology("Gastrointestinal System/physiology GastroscopyGene Expression82Gene Expression Regulation, Enzymologic/physiology,'Gene Expression/drug effects/physiology Gene Expression/physiology($Gills/anatomy & histology/physiologyGills/physiologyGlucose/pharmacologyGlutamates/*pharmacologyGlutamates/*physiologyGlutamates/metabolismGlutamates/pharmacology("Glutamates/pharmacology/physiologyGlutamates/physiology,&Glutamic Acid/*metabolism/pharmacology Glutamic Acid/*pharmacologyGlutamic Acid/*physiology(%Glutamic Acid/pharmacology/physiology Glycopeptides/pharmacology("Glycoproteins/*analysis/immunologyGrasshoppers/*physiology85GTP-Binding Protein alpha Subunits, Gq-G11/metabolism85Guanylate Cyclase/antagonists & inhibitors/metabolism Guanylate Cyclase/metabolism Guinea Pigs("Heart Conduction System/physiology$Heart/drug effects/*physiology Heart/embryology/innervationHeart/innervation Heart/innervation/physiologyHeart/physiologyHeat Hemicholinium 3/pharmacologyHemolymph/chemistry$Hemolymph/immunology/metabolismHemolymph/metabolismHistamine/*analysis<8Histamine/administration & dosage/*metabolism/physiologyHistamine/metabolism("Histamine/pharmacology/*physiologyHistocytochemistryHistological Techniques$History of Medicine, 20th Cent. HomeostasisHomeostasis/*physiologyHoof and Claw/innervationHorseradish Peroxidase("Horseradish Peroxidase/*metabolism Horseshoe Crabs/*physiologyHorseshoe Crabs/chemistryHuman Humans Ibotenic Acid/pharmacologyImmobilizationImmune Sera/immunologyImmunochemistryImmunoenzyme TechniquesImmunohistochemistry Immunohistochemistry/methodsImmunologic Techniques In Vitro Inhibitioninhibitors/*drug effects Injections,(Inositol 1,4,5-Trisphosphate/*metabolism,(Insect Hormones/*pharmacology/physiology,'Insect Hormones/metabolism/pharmacology Insects$Insects/*metabolism/physiologyInsects/*physiologyInterneurons/*chemistryInterneurons/*physiology($Interneurons/drug effects/physiologyInterneurons/physiology,&Interneurons/physiology/ultrastructure(#interruptus stomatogastric ganglion intersegmental coordinationIntestines/innervation$!Intestines/innervation/physiology(#Invertebrate Hormones/*pharmacology$!Invertebrate Hormones/*physiology$Invertebrate Hormones/analysis0-Invertebrate Hormones/metabolism/pharmacology("Invertebrate Hormones/pharmacology InvertebratesInvertebrates/*chemistryInvertebrates/*physiologyInvertebrates/physiology Ion Channel Gating/physiology Ion Channels/*drug effectsIon Channels/*physiology41Ion Channels/antagonists & inhibitors/*metabolismIon Channels/drug effects(%Ion Channels/drug effects/*physiology($Ion Channels/drug effects/metabolism($Ion Channels/drug effects/physiologyIon Channels/metabolismIon Channels/physiologyIonsIons/*metabolism Iontophoresis Isoquinolinesb"\97143370VOHarris-Warrick, R. M. Coniglio, L. M. Levini, R. M. Gueron, S. Guckenheimer, J.tnDopamine modulation of two subthreshold currents produces phase shifts in activity of an identified motoneuronAnimal Differential Threshold Dopamine/pharmacology/*physiology Electric Conductivity Ganglia, Invertebrate/cytology/physiology Lobsters Models, Neurological Motor Neurons/drug effects/*physiology Neural Inhibition Patch-Clamp Techniques Periodicity Potassium/physiology Pylorus/innervation/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiologym@91. The lateral pyloric (LP) neuron is a component of the 14-neuron pyloric central pattern generator in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. In the pyloric rhythm, this neuron fires rhythmic bursts of action potentials whose phasing depends on the pattern of synaptic inhibition from other network neurons and on the intrinsic postinhibitory rebound properties of the LP cell itself. Bath-applied dopamine excites the LP cell and causes its activity to be phase advanced in the pyloric motor pattern. At least part of this modulatory effect is due to dopaminergic modulation of the intrinsic rate of postinhibitory rebound in the LP cell. 2. The LP neuron was isolated from all detectable synaptic input. We measured the rate of recovery after 1-s hyperpolarizing current injections of varying amplitudes, quantifying the latency to the first spike following the hyperpolarizing prepulse and the interval between the first and second action potentials. Dopamine reduced both the first spike latency and the first interspike interval (ISI) in the isolated LP neuron. During the hyperpolarizating pre-steps, the LP cell showed a slow depolarizing sag voltage that was enhanced by dopamine. 3. We used voltage clamp to analyze dopamine modulation of subthreshold ionic currents whose activity is affected by hyperpolarizing prepulses. Dopamine modulated the transient potassium current IA by reducing its maximal conductance and shifting its voltage dependence for activation and inactivation to more depolarized voltages. This outward current is normally transiently activated after hyperpolarization of the LP cell, and delays the rate of postinhibitory rebound; by reducing IA, dopamine thus accelerates the rate of rebound of the LP neuron. 4. Dopamine also modulated the hyperpolarization-activated inward current Ih by shifting its voltage dependence for activation 20 mV in the depolarizing direction and accelerating its rate of activation. This enhanced inward current helps accelerate the rate of rebound in the LP cell after inhibition. 5. The relative roles of Ih and IA in determining the first spike latency and first ISI were explored using pharmacological blockers of Ih (Cs+) and IA [4-aminopyridine (4-AP)]. Blockade of Ih prolonged the first spike latency and first ISI, but only slightly reduced the net effect of dopamine. In the continued presence of Cs+, blockade of IA with 4-AP greatly shortened the first spike latency and first ISI. Under conditions where both Ih and IA were blocked, dopamine had no additional effect on the LP cell. 6. We used the dynamic clamp technique to further study the relative roles of IA and Ih modulation in dopamine's phase advance of the LP cell. We blocked the endogenous Ih with Cs+ and replaced it with a simulated current generated by a computer model of Ih. The neuron with simulated Ih gave curves relating the hyperpolarizing prepulse amplitude to first spike latency that were the same as in the untreated cell. Changing the computer parameters of the simulated Ih to those induced by dopamine without changing IA caused only a slight reduction in first spike latency, which was approximately 20% of the total reduction caused by dopamine in an untreated cell. Bath application of dopamine in the presence of Cs+ and simulated Ih (with control parameters) allowed us to determine the effect of altering IA but not Ih: this caused a significant reduction in first spike latency, but it was still only approximately 70% of the effect of dopamine in the untreated cell. Finally, in the continued presence of dopamine, changing the parameters of the simulated Ih to those observed with dopamine reduced the first spike latency to that seen with dopamine in the untreated cell. 7. We generated a mathematical model of the lobster LP neuron, based on the model of Buchholtz et al. for the crab LP neuron.J Neurophysiol 19957441404-20d^Harris-Warrick, R.M. Baro, D.J. Coniglio, L.M. Johnson, B.R. Levini, R.M. Peck, J.H. Zhang, B. 1997RKChemical modulation of crustacean stomatogastric pattern generator networks >8Stein, P.S.G. Grillner, S. Selverston, A.I. Stuart, D.G.*#Neuron, Networks and Motor Behavior  Cambridge, MA+  MIT Press209-215XRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9928309`YHarris-Warrick, R. M. Johnson, B. R. Peck, J. H. Kloppenburg, P. Ayali, A. Skarbinski, J. RLDistributed effects of dopamine modulation in the crustacean pyloric networkAnimal Crustacea Dopamine/*physiology Ganglia, Invertebrate/chemistry/cytology/physiology Motor Neurons/chemistry/*physiology Pylorus/innervation Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.tIt is now clear that neuromodulators can reconfigure a single motor network to allow the generation of a family of related movements. Using dopamine modulation of the 14-neuron pyloric network from the crustacean stomatogastric ganglion as an example, we describe two major mechanisms by which network output is modulated. First, the baseline electrophysiological properties of the network neurons can be altered. Dopamine can affect the activity of each neuron independently. For example, DA modulates IA in nearly every neuron in the pyloric network, but in opposite directions in different cells. Furthermore, DA usually modulates combinations of ionic currents. In some cases, currents with opposing actions on cell excitability are simultaneously affected, and the net response reflects the sum of these opposing effects. Second, neuromodulators can alter the strength of synaptic interactions within the network, quantitatively "rewiring" the network. Every synapse in the network is affected by DA, with some increased and others decreased in strength. DA acts both pre- and postsynaptically to affect transmission: these actions are frequently opposing in sign, and the net response arises as the sum of these opposing actions. Finally, spike-evoked and graded transmission at the same synapse can be oppositely affected by DA. These results emphasize the distributed nature of modulation in motor networks.n'ngSection of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, USA. rmh4@cornell.edue9928309Ann N Y Acad Sci 1998 860155-67.12490254126A 2002 Dec0>8Voltage-sensitive ion channels in rhythmic motor systems 646-51Voltage-sensitive ionic currents shape both the firing properties of neurons and their synaptic integration within neural networks that drive rhythmic motor patterns. Persistent sodium currents underlie rhythmic bursting in respiratory neurons. H-type pacemaker currents can act as leak conductances in spinal motoneurons, and also control long-term modulation of synaptic release at the crayfish neuromuscular junction. Calcium currents travel in rostro-caudal waves with motoneuron activity in the spinal cord. Potassium currents control spike width and burst duration in many rhythmic motor systems. We are beginning to identify the genes that underlie these currents.'tnDepartment of Neurobiology and Behavior, Seeley G. Mudd Hall, Cornell University, 14853, Ithaca, New York, USAHarris-Warrick, R. M.("22378506 0959-4388 Journal ArticleCurr Opin Neurobiollehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12490254sis of Variance Animal9435160360Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.|vDifferential modulation of chemical and electrical components of mixed synapses in the lobster stomatogastric ganglionxqAnimal Biogenic Amines/*pharmacology Dopamine/pharmacology Electrophysiology Ganglia, Invertebrate/*physiology Lobsters/*physiology Neural Inhibition/drug effects Neuronal Plasticity Octopamine/pharmacology Pylorus/*innervation Serotonin/pharmacology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*drug effects/*physiologya 1. Two pairs of neurons in the pyloric network of the spiny lobster, Panulirus interruptus, communicate through mixed graded chemical and rectifying electrical synapses. The anterior burster (AB) chemically inhibits and is electrically coupled to the ventricular dilator (VD); the lateral pyloric (LP) and pyloric (PY) neurons show reciprocal chemical inhibition and electrical coupling. We examined the effects of dopamine (DA), serotonin (5HT) and octopamine (Oct) on these mixed synapses to determine the plasticity possible with opposing modes of synaptic interaction. 2. Dopamine increased net inhibition at all three pyloric mixed synapses by both reducing electrical coupling and increasing chemical inhibition. This reversed the sign of the net synaptic interaction when electrotonic coupling dominated some mixed synapses, and activated silent chemical components of other mixed synapses. 3. Serotonin weakly enhanced LP-->PY net inhibition, by reducing electrical coupling without altering chemical inhibition. Serotonin reduced AB-->VD electrical coupling, but variability in its effect on the chemical component made the net effect non-significant. 4. Octopamine enhanced LP-->PY and PY-->LP net inhibition by enhancing the chemical inhibitory component without altering electrical coupling. 5. Differential modulation of chemical and electrical components of mixed synapses markedly changes the net synaptic interactions. This contributes to the flexible outputs that modulators evoke from anatomically defined neural networks.J Comp Physiol [A] 1994 1752 233-49 :4 80043197("Hartline, D. K. Gassie, D. V., Jr.{Pattern generation in the lobster (Panulirus) stomatogastric ganglion. I. Pyloric neuron kinetics and synaptic interactionsAdaptation, Physiological Animal Ganglia/*physiology Kinetics Lobsters Membrane Potentials Models, Neurological Nerve Net/physiology Neurons/*physiology Periodicity Pylorus/*innervation Stomach/innervation Support, U.S. Gov't, P.H.S. Synapses/*physiologyThere are a number of perspectives gained from a quantitative analysis of the pyloric system which may be applicable to other simple pattern generators: 1. The system is organized around a dominant, endogenously- bursting neuron group, and its properties are tailored to that dominance. In particular, synaptic strengths and firing frequencies of that group appear just sufficient to suppress postsynaptic "follower" cells if the latter are not too highly excited. 2. Repetitive firing properties of follower neurons are such as to facilitate their switch- like mode of activity. This includes pacemaker response nonlinearities, rebound properties, and "burstiness" properties. 3. Proper sequencing of follower cells may be controlled by particular synaptic strengths and time-courses, feedback on the oscillator cells, and functional cellular properties of follower neurons (e.g., rebound; see also next paper). All such properties interact and must be tuned to each other for proper patterns to result. Biol Cybern 1979334 209-2285056950$Hartline, D. K. Russell, D. F.~xEndogenous burst capability in a neuron of the gastric mill pattern generator of the spiny lobster Panulirus interruptuspiAnimal Electrophysiology Female Ganglia/*physiology Lobsters Male Periodicity Support, U.S. Gov't, P.H.S.i D >The gastric system of the lobster stomatogastric ganglion has previously been thought to include no neurons capable of endogenous bursting. We describe conditions under which one of the motorneurons, the CP cell, can burst endogenously in a free-running manner in the absence of other phasic network activity. Isolated preparations of the foregut nervous system were used, and the CP bursting was either spontaneous or was activated by continuous stimulation of an input nerve. Three criteria were applied to establish the endogenous nature of such burst generation in CP: absence of phasic input, reset of the bursting pattern by pulses of current in a characteristic phase- dependent manner, and modulation of burst rate by sustained injected current. (1) The firing of other cells which are known to be related synaptically to CP was monitored in nerve records. These other cells were either silent or fired only tonically. Cross-correlograms showed that CP bursting was not ascribable to phasic activity in these other network cells. (2) A depolarizing current pulse of sufficient strength injected intracellularly between bursts triggered a burst prematurely and reset the subsequent rhythm. A hyperpolarizing pulse during a burst terminated it and reset the subsequent rhythm. Reset behavior was similar to that described for other endogenous bursters. (3) Application of a positive-going ramp current initially caused an increase in burst rate, as described for other endogenous bursters. However, further depolarization caused a slower burst rate due to lengthening of the individual bursts, although mean firing frequency continued to increase throughout the range tested. Such free-running endogenous repetitive bursting appeared to result from the CP's ability to produce slow regenerative depolarizations ("plateau potentials"). When bursting was present, so was the plateau property, as determined by I-V analysis and by the ability of brief current pulses to trigger and terminate bursts. The previous inability to observe endogenous bursting in preparations with central input removed may be due to the usual absence of the plateau property in such preparations. CP bursting during normal gastric mill rhythms, while underlain by plateau potentials, is strongly controlled by network interactions. CP appears not to be well placed in the network to be considered a source of normal gastric rhythmicity. Nevertheless, endogenous bursting in CP may explain some of the partial gastric rhythms seen in behavioral studies, and illustrates one way that cellular properties might contribute to rhythmic behaviors. J Neurobiol 1984155 345-64Hartline, D.K. 1987& Modeling stomatogastric ganglion "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-Verlag181-197Hartline, D.K. 1987Plateau potential  Adelman, G."Encyclopedia of Neuroscience Boston  Birkhauser955-9560)Hartline, D.K. Gassie, D.V. Sirchia, C.D.a 1987j9PY cell types in the stomatogastric ganglion of Panulirus 0 "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-VerlagThe Crustacean 75-7789090479>8Hartline, D. K. Russell, D. F. Raper, J. A. Graubard, K.JDSpecial cellular and synaptic mechanisms in motor pattern generationAnimal Crustacea/*physiology Motor Neurons/cytology/*physiology Support, U.S. Gov't, P.H.S. Synapses/*physiology Synaptic Transmission 1988Comp Biochem Physiol C9114 115-31 Using Smart Source ParsingHartline, D.K. 1989JDSimulation of restricted neural networks with reprogrammable neurons"IEEE Trans Circuits Systems36653-660Hartline, D.K. 1991JCThe neuron as a reprogrammable computing element in neural networks  Fraser, M.ZSAdvances in Control Networks and Large Scale Parallel Distributed Processing Models  Norwood, NJ Ablex 58-82"Hartline, D.K. Graubard, K. 1992VPCellular and synaptic properties in the crustacean stomatogastric nervous system BDymanic Biological Networks: The Stomatogastric Nervous System  Cambridge, MA  MIT Press 31-86&87011461NHHooper, S. L. O'Neil, M. B. Wagner, R. Ewer, J. Golowasch, J. Marder, E.The innervation of the pyloric region of the crab, Cancer borealis: homologous muscles in decapod species are differently innervatedAcetylcholine/pharmacology Crabs Curare/pharmacology Electric Conductivity Electric Stimulation Ganglia/physiology Glutamates/pharmacology Motor Neurons/drug effects/*physiology Muscles/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.piThe muscles of the pyloric region of the stomach of the crab, Cancer borealis, are innervated by motorneurons found in the stomatogastric ganglion (STG). Electrophysiological recording and stimulating techniques were used to study the detailed pattern of innervation of the pyloric region muscles. Although there are two Pyloric Dilator (PD) motorneurons in lobsters, previous work reported four PD motorneurons in the crab STG (Dando et al. 1974; Hermann 1979a, b). We now find that only two of the crab PD neurons innervate muscles homologous to those innervated by the PD neurons in the lobster, Panulirus interruptus. The remaining two PD neurons innervate muscles that are innervated by pyloric (PY) neurons in P. interruptus. The innervation patterns of the Lateral Pyloric (LP), Ventricular Dilator (VD), Inferior Cardiac (IC), and PY neurons were also determined and compared with those previously reported in lobsters. Responses of the muscles of the pyloric region to the neurotransmitters, acetylcholine (ACh) and glutamate, were determined by application of exogenous cholinergic agonists and glutamate. The effect of the cholinergic antagonist, curare, on the amplitude of the excitatory junctional potentials (EJPs) evoked by stimulation of the pyloric motor nerves was measured. These experiments suggest that the differences in innervation pattern of the pyloric muscles seen in crab and lobsters are also associated with a change in the neurotransmitter active on these muscles. Possible implications of these findings for phylogenetic relations of decapod crustaceans and for the evolution of neural circuits are discussed.J Comp Physiol [A] 1986 1592 227-4087282571Hooper, S. L. Marder, E.HAModulation of the lobster pyloric rhythm by the peptide proctolin(!Action Potentials Animal Digestive System/innervation Female Ganglia/physiology Interneurons/drug effects/physiology Lobsters/*physiology Male Motor Neurons/*physiology Nervous System/drug effects/*physiology *Nervous System Physiology Oligopeptides/*physiology Support, U.S. Gov't, P.H.S.hPJThe modulation of the pyloric network of the stomatogastric ganglion (STG) of the lobster Panulirus interruptus by the neuropeptide proctolin is described. First, the effects of proctolin on the pyloric motor patterns were characterized in terms of frequency and phase relations. Pyloric cycle frequency and lateral pyloric (LP) neuron activity increased and ventricular dilator (VD) neuron activity decreased with increasing concentrations (10(-9)-10(-6) M) of applied proctolin. Next, the effects of proctolin on the individual neurons that constitute the pyloric network were determined. Identified neurons were isolated from chemical and electrical presynaptic inputs by using pharmacological agents (Marder and Eisen, 1984a) and/or photoinactivation following Lucifer yellow injection (Miller and Selverston, 1979). Proctolin increased the amplitude and frequency of bursts produced by isolated pacemaker anterior burster (AB) neurons. Isolated LP and pyloric (PY) neurons responded to proctolin with increases in activity only when they were at or above threshold. All other pyloric neurons were unaffected. To determine how the direct effects of proctolin on isolated neurons resulted in the observed changes in frequency and phase relations in the motor pattern of the intact pyloric circuit seen in proctolin, individual neurons were deleted from the circuit. A comparison of proctolin's effects on isolated neurons with those on the intact network shows that the synaptic connectivity among neurons directly affected by proctolin and those unaffected by it shapes the network's response to proctolin. J Neurosci 19877d7o2097-11289298390 Hooper, S. L. Moulins, M.cjcSwitching of a neuron from one network to another by sensory-induced changes in membrane properties82Action Potentials Animal Cell Membrane/physiology Electric Stimulation Lobsters/*physiology Membrane Potentials Nervous System/cytology/*physiology *Nervous System Physiology Neural Pathways/cytology/physiology Neurons/*physiology Stomach/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.A neuron that is an integral member of the pyloric neural network of the lobster stomatogastric nervous system leaves this network and instead fires exclusively with another stomatogastric nervous system network, the cardiac sac network, whenever the cardiac sac network is active. This switch is associated with the neuron losing, in a long- lasting fashion, regenerative oscillatory membrane properties that underlie its participation in the pyloric network. Functional membership of neurons in central networks is thus not fixed, and long- lasting neuromodulatory influences, controlled at least in part by sensory inputs, can switch neurons from one network to another.Science 1989 244 4912 1587-9 ". 933532410*Hartline, D. K. Gassie, D. V. Jones, B. R.~xEffects of soma isolation on outward currents measured under voltage clamp in spiny lobster stomatogastric motor neurons~Animal Calcium/physiology Computer Simulation Electrophysiology Female Ganglia/cytology/physiology In Vitro Ion Channels/*physiology Kinetics Lobsters/*physiology Male Membrane Potentials/physiology Microelectrodes Models, Neurological Motor Neurons/*physiology Neurites/physiology Pylorus/innervation Stomach/*innervation Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.F?1. Outward currents in identified cell types from the pyloric system of the stomatogastric ganglion (STG) of the spiny lobster, Panulirus marginatus, were studied under two-microelectrode voltage clamp. A comparison was made between data from intact cells and somata isolated by ligation of the primary neurite of these monopolar neurons. 2. Despite the elimination of current contributions from the extensive arborizations of STG neurons, few significant differences were found in the mean values of parameters for outward currents between populations of isolated somata and intact cells of a given type. Measurements that showed little difference included magnitude and activation threshold of a calcium-dependent outward current (IJ) and magnitude, activation threshold, voltage dependence, and inactivation time course of A current (IA). Although previous work has suggested that IJ might reside predominantly in the soma, IA is known to be distributed in poorly space-clamped neurite processes. The absence of obvious effects of isolation was thus unexpected. 3. To better understand the mechanisms involved, we used compartmental models derived from reconstructed neurons to simulate the effects of isolation. It was concluded that, for the particular conditions present in stomatogastric neurons, with a large, uniformly distributed outward current conductance activated, even though neurites and axon remain attached, most measured current flows through well-clamped soma membrane. 4. Factors contributing to this result included the outward sign of the current, the large specific conductance activated in these neurons (among the larger reported in somata), and the presence of only a single major process leaving the soma. The potential for serious errors in voltage-clamp measurements from intact cells remains if these conditions are not met.J Neurophysiol 19936962056-7112766427143w 2003May-JunrztSimulations of voltage clamping poorly space-clamped voltage-dependent conductances in a uniform cylindrical neurite 253-69Significant error is made by using a point voltage clamp to measure active ionic current properties in poorly space-clamped cells. This can even occur when there are no obvious signs of poor spatial control. We evaluated this error for experiments that employ an isochronal I(V) approach to analyzing clamp currents. Simulated voltage clamp experiments were run on a model neuron having a uniform distribution of a single voltage-gated inactivating ionic current channel along an elongate, but electrotonically compact, process. Isochronal Boltzmann I(V) and kinetic parameter values obtained by fitting the Hodgkin-Huxley equations to the clamp currents were compared with the values originally set in the model. Good fits were obtained for both inward and outward currents for moderate channel densities. Most parameter errors increased with conductance density. The activation rate parameters were more sensitive to poor space clamp than the I(V) parameters. Large errors can occur despite "normal"-looking clamp curves.i'Bekesy Laboratory of Neurobiology, Pacific Biomedical Research Center, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, HI 96822.*#Hartline, D. K. Castelfranco, A. M.("22651244 0929-5313 Journal ArticleJ Comput Neuroscilehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12766427DHeinzel, H. G. 1987{Appendix B: Spontaneous and proctolin-induced modes of operation of the isolated gastric oscillator and of the gastric mill "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-Verlag 175-180&Heinzel, H. G. Selverston, A.I. 1987LFReset analysis of the gastric central pattern generator in the lobster Elsner, N. Creutzfeldt, O..(New Frontiers in Crustacean Neurobiology New York Thieme Stuttgart67Heinzel, H. G. 1988xGSensory control of the stomatogastric system in the crab Cancer pagurus\9 Elsner, N. Barth, G.@9Sense Organs, Interfaces Between Environment and Behaviora New York Thieme Stuttgart 82-11588171656Heinzel, H. G.LEGastric mill activity in the lobster. I. Spontaneous modes of chewingtAnimal Biomechanics *Dentition Lobsters/*physiology Male *Mastication Muscles/physiology Reflex/physiology Stomach/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Time Factorsh|v1. The gastric central pattern generator (CPG) driving the three teeth of the gastric mill inside the lobster stomach has often been used as a model for the study of central nervous systems, but the actual functioning of the mill has never been observed directly. By using a small endoscope inserted through the esophagus a video analysis of the tooth movements was performed with restrained, but otherwise intact lobsters. 2. The teeth show spontaneous periodic chewing (cycle duration from 4 to 70 s) in two different basic modes. In the squeeze mode only the cusps of the three teeth move together simultaneously. In the cut-and-grind mode the lateral teeth close first with not only their cusps, but also their serrated edges. After this cut phase the lateral teeth grind backward along the file of the medial tooth, which simultaneously moves forward. 3. Simultaneous endoscope recordings of the teeth, filming of stomach muscles and ossicles combined with electrical stimulation of selected muscles reveal that muscle gm3c is responsible for this hitherto unknown backward grinding of the lateral teeth. 4. The complete behavioral repertoire includes the following modifications of the two basic modes. 1) The lateral teeth can perform chewing movements while the medial tooth stays still and vice versa, forms of chewing regarded even weaker than the squeeze. 2) There do not appear to be intermediates between the squeeze and cut-and-grind movements, with the latter as the strongest form of chewing. Transitions only occur as switching on a cycle-by-cycle basis. 3) A gradual change of the cut-and-grind chewing was observed as the gradual development of an additional opening over the time course of several periods. 4) After their grind phase, the lateral teeth can even move further back beyond the medial tooth. This can serve to push food into the pyloric filter apparatus. 5. Inflation of the cardiac sac can elicit single bites in a resting gastric mill. 6. The behavioral repertoire is compared with the in vivo activity of the gastric oscillator represented by simultaneous intracellular recording from 7 representative cells of the 11 CPG neurons.J Neurophysiol 1988592 528-50$HAHemple, C.M. Vincent, P. Adams, S.R. Tsien, R.Y. Selverston, A.I. 1996PJSpatio-temporal dynamics of cyclic AMP signals in an intact neural circuit Nature 384166-169Hermann, A. Dando, M.R. 1977Mechanisms of command fibre operation onto butsting pacemaker neurons in the stomatogastric ganglion of the crab, Cancer pagurusrJ Comp Physiol 114 15-33p Hermann, A. 1979Generation of a fixed motor pattern. I. Details of synaptic interconnections of pyloric neurons in the stomatogastric ganglion of the crab, Cancer pagurusJ Comp Physiol 130221-228 Hermann, A. 1979Generation of a fixed motor pattern. II. Electrical properties and synaptic characteristics of pyloric neurons in the stomatogastric ganglion of the crab, Cancer pagurusJ Comp Physiol 130229-23982026425 Hermann, A. ZTAction of caffeine on pyloric motorneurons in the crustacean stomatogastric ganglionAction Potentials/drug effects Animal Caffeine/*pharmacology Crabs/*physiology Crayfish/*physiology Ganglia/*drug effects Membrane Potentials/drug effects Motor Neurons/*drug effects Ouabain/pharmacology Pylorus/cytology/drug effects  1981Comp Biochem Physiol C692P 191-7l Using Smart Source ParsingHermann, A. Wadepuhl, M. 1987B;Ionic basis of pacemaker activity in stomatogastric neurons "Selverston, A.I. Moulins, M.*$The Crustacean Stomatogastric System Berlin Springer-Verlag101-107PHinton, D.J. Corey, S. 1979~MThe mouthparts and digestive tract in the larval stages of Homarus americanus; Can J Zool57 1413-1423i84258552Hooper, S. L. Marder, E.^WModulation of a central pattern generator by two neuropeptides, proctolin and FMRFamide Animal Comparative Study Crabs/*physiology Ganglia/*drug effects/metabolism In Vitro Motor Neurons/drug effects Neurotransmitters/*pharmacology Oligopeptides/metabolism/*pharmacology Stimulation, Chemical Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.The neuropeptides, proctolin and FMRFamide, increase the frequency of, and modify the motor pattern produced by, the stomatogastric ganglion (STG) of the crab, Cancer irroratus. Both proctolin-like and FMRFamide- like immunoreactivities are present in fibers in the stomatogastric nerve which terminate in the neuropile of the STG. The neural output of the STG thus appears to be modulated by at least two different groups of peptidergic input fibers.) Brain Resd 1984 305o1n 186-91,s/*metabolism Animal9226042260Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.ztElevated temperature alters the ionic dependence of amine-induced pacemaker activity in a conditional burster neuronleAnimal Biogenic Amines/*physiology Biological Clocks/*physiology Calcium/metabolism Dopamine/physiology Heat In Vitro Lobsters/*physiology Magnesium/metabolism Membrane Potentials/physiology Neurons/*physiology Octopamine/physiology Serotonin/physiology Sodium/metabolism Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tetrodotoxin/pharmacologyJThe anterior burster neuron of the lobster (Panulirus interruptus) stomatogastric ganglion is a conditional burster that functions as the primary pacemaker for the pyloric motor network. When modulatory inputs to this cell are blocked, it loses its bursting properties and becomes quiescent. Applications of the monoamines, dopamine, octopamine or serotonin restore rhythmic bursting in this cell (Flamm and Harris- Warrick 1986). At 15 degrees C, serotonin- and octopamine-induced oscillations depend critically upon sodium entry (blocked by low sodium saline or tetrodotoxin); dopamine-induced oscillations depend upon calcium entry (blocked by reduced extracellular calcium; Harris-Warrick and Flamm 1987). We show here that the ionic dependence of amine- induced oscillations in the anterior burster cell differs at 15 and 21 degrees C. At 21 degrees C, all amines have the potential to induce rhythmic oscillations in saline containing tetrodotoxin. At the elevated temperature and in tetrodotoxin, both calcium and sodium currents are essential for the maintenance of dopamine-induced oscillations; serotonin-induced oscillations do not depend upon either calcium or sodium alone; octopamine-induced oscillations do not depend upon calcium and show a variable dependence upon sodium. Thus, multiple ionic mechanisms, which vary with both the modulator and the ambient temperature, can be recruited to support rhythmic activity in a conditional burster neuron.eJ Comp Physiol [A] 1992 170 2d 201-9t> t 688171657Heinzel, H. G.f`Gastric mill activity in the lobster. II. Proctolin and octopamine initiate and modulate chewing& Animal *Dentition Dose-Response Relationship, Drug Injections Lobsters/*physiology *Mastication/drug effects Octopamine/pharmacology/*physiology Oligopeptides/pharmacology/*physiology Reflex/drug effects Stomach/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Time FactorsLE1. The neuromodulators proctolin and octopamine were injected into the circulatory system of lobsters, and the subsequent reaction of their gastric mill was analyzed with the help of an endoscope. 2. Injections of proctolin into the dorsal heart sinus elicited chewing with period durations of 5-60 s after a latency of 53 +/- 42 s (n = 32 injections). The threshold dose was 1 ml of 1.5 X 10(-7) M, which results in an estimated concentration of 3 X 10(-9) M in the blood. 3. The effects of proctolin on the coordination of the three teeth of the gastric mill is dose dependent. Proctolin injections of 1 ml of 1.5 X 10(-6) M elicited chewing in the squeeze mode, 1 ml of 1.5 X 10(-4) M triggered chewing in the cut-and-grind mode. Both modes are different in terms of coordination and usage of functionally different parts of the teeth. 4. An increase in the proctolin dose causes an increase of the duty cycle (ratio of closing duration to period duration) of the chewing from 0.19 to 0.51. The corresponding period duration shortens (from 30.8 to 9.9 s) at intermediate doses, but lengthens to 16.6 s at high doses because the closing duration goes up. 5. Chewing following a single injection can last between 2 and 30 min. Besides more or less stereotypic chewing in one of the basic modes, variations occurred, such as chewing of just the lateral teeth, cycle-by-cycle switching between different modes, or double bites of either the lateral teeth or the medial tooth. 6. Proctolin increased the strength of reflex bites, which could be elicited by mechanical stimulation of the cardiac sac. 7. Octopamine elicited not only irregular chewing, but also other reactions such as struggling, only if high doses, between 1 ml of 1.5 X 10(-4) and 1.5 X 10(-3) M were given, which correspond to an estimated concentration in the blood of between 3 X 10(-6) and 3 X 10(-5) M. 8. The proctolin effects on the gastric mill match the spontaneously occurring behavioral repertoire of the gastric mill, and they are explainable with known properties of the gastric central pattern generator and its sensitivity to proctolin.J Neurophysiol 1988592 551-6588171658& Heinzel, H. G. Selverston, A. I.piGastric mill activity in the lobster. III. Effects of proctolin on the isolated central pattern generatorVPAnimal *Dentition Dose-Response Relationship, Drug Ganglia/cytology/*drug effects/physiology In Vitro Lobsters/*physiology Motor Neurons/drug effects/physiology Nerve Block Nervous System/physiology Nervous System Physiology Oligopeptides/*pharmacology Stomach/innervation/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. > 81. The response of the isolated gastric central pattern generator (CPG) to bath application of proctolin is characterized and compared with the previously analyzed behavioral response. 2. Proctolin had an excitatory effect on the ongoing spontaneous rhythm of "combined" preparations, in which the stomatogastric ganglion (STG) is connected to the esophageal and commissural ganglia by the stomatogastric nerve (STN). The effect started between 20 s and 5 min and was characterized by strongly increased burst durations as well as increased spike rates in all units except the two lateral posterior gastric (LPG) motoneurons. The effect was strongest in the dorsal gastric (DG) and lateral gastric (LG) motoneurons and was accompanied by a phase change of the DG burst. DG continued spiking throughout large parts of the burst of LG and of the gastric mill (GM) motoneurons, which are antagonists of DG. 3. The threshold concentration was approximately 10(-10) M, and the effects were dose dependent and reversible. 4. LG and DG were identified as target cells for the action of proctolin. In LG regenerative plateau properties were induced, as revealed by its long-lasting plateau potentials, sensitivity for triggering inputs, and the occurrence of oscillatory prepotentials. An induction of endogenous bursting in DG was concluded from preparations, in which DG was cycling alone or bursting with a much shorter period duration than other gastric neurons. Hyperpolarization of DG, which normally has no or weak driving power within the gastric network, demonstrated that under the influence of proctolin, firing of DG can accelerate the gastric rhythm from a 27- to a 9-s period duration. 5. Proctolin does not only have a modulatory influence on an ongoing rhythm, but it also can trigger gastric activity. This function was first concluded from proctolin-treated STGs, which, unlike normal preparations, continue bursting if inputs via the STN are blocked. Finally, triggering was demonstrated directly, since isolated STGs that were not oscillating started a gastric rhythm after 20-30 min of perfusion with proctolin. 6. The proctolin-induced changes of the CPG activity in isolated preparations are in agreement with the effect on gastric mill chewing in the intact animal, in which, depending on the dose, different modes of chewing could be elicited.J Neurophysiol 1988592 566-85Heinzel, H. G. 1990^The cooperation of several oscillators in the stomatogastric system of the crab Cancer pagurusP @:Wiese, K. Krenz, W.-D. Tautz, J. Reichert, H. Mulloney, B.*$Frontiers in Crustacean Neurobiology Basel Verlag455-462+Heinzel, H. G. 1990D=Modulation and sensory control of the crustacean gastric mill3 0)Erber, J. Menzel, R. Pfluger, H. Todt, D.r$Neural Mechanisms of Behavior  Stuttgart Georg Thieme Verlag_ 61-66_*$Heinzel, H. G. Bohm, H. Weigeldt, D. 1993^XThe cooperation of neural nerworks as the basis for the plasticity of rhythmic movementsVerh Dtsch Zool Ges86165-17693217558.(Heinzel, H. G. Weimann, J. M. Marder, E.The behavioral repertoire of the gastric mill in the crab, Cancer pagurus: an in situ endoscopic and electrophysiological examination 60Animal Behavior, Animal/physiology Comparative Study *Digestive Physiology Digestive System/innervation/*physiology Electrophysiology Female Ganglia/cytology/physiology Gastroscopy Male Neurons/physiology Periodicity Pylorus/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Tooth/physiologySimultaneous endoscopic and electrophysiological recordings were used to observe the behavior of the gastric mill complex while recording the motor output of the stomatogastric ganglion (STG) in intact crabs. In the crab STG, many pattern-generating neurons are able to fire in several distinct rhythmic motor patterns. Specifically, many neurons can switch between firing in time with the rapid pyloric rhythm to firing in time with the slower gastric mill rhythm (Weimann et al., 1991). We now correlate behaviorally relevant movements of the gastric mill with some of the modifications of neuronal firing patterns previously characterized using in vitro STG preparations. The intracellular and extracellular recordings from the intact crab are largely indistinguishable from those obtained from in vitro preparations. For the first time, we describe the movements that result as neurons switch their activity patterns associated with activation of the gastric mill rhythm. Extracellular stimulation and intracellular depolarization of individual motor neurons is used to determine the relationship between frequency of firing and movement in behaving animals. J Neurosci 1993134o1793-803 1500442313 1-2n 2004Jan-Apr PIThe insect frontal ganglion and stomatogastric pattern generator networksl 20-36aInsect neural networks have been widely and successfully employed as model systems in the study of the neural basis of behavior. The insect frontal ganglion is a principal part of the stomatogastric nervous system and is found in most insect orders. The frontal ganglion constitutes a major source of innervation to foregut muscles and plays a key role in the control of foregut movements. Following a brief description of the anatomy and development of the system in different insect groups, this review presents the current knowledge of the way neural networks in the insect frontal ganglion generate and control behavior. The frontal ganglion is instrumental in two distinct and fundamental insect behaviors: feeding and molting. Central pattern-generating circuit(s) within the frontal ganglion generates foregut rhythmic motor patterns. The frontal ganglion networks can be modulated in-vitro by several neuromodulators to generate a variety of motor outputs. Chemical modulation as well as sensory input from the gut and input from other neural centers enable the frontal ganglion to induce foregut rhythmic patterns under different physiological conditions. Frontal ganglion neurons themselves are also an important source of neurosecretion. The neurosecretory material from the frontal ganglion can control and modulate motor patterns of muscles of the alimentary canal. The current and potential future importance of the insect stomatogastric nervous system and frontal ganglion in the study of the neural mechanisms of behavior are discussed.'rlDepartment of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. ayali@post.tau.ac.il Ayali, A. & 1424-862x Journal Article Review Neurosignals2+Animals Behavior, Animal Digestive System/innervation/metabolism Electric Stimulation Feeding Behavior/physiology Ganglia, Invertebrate/anatomy & histology/*physiology Insects Molting/physiology Nerve Net/cytology/*physiology *Nervous System Physiology *Neural Networks (Computer) Neurons/physiology lehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15004423AM V151753832422 2004 Jun 2e|Dynamic interaction of oscillatory neurons coupled with reciprocally inhibitory synapses acts to stabilize the rhythm period5140-50dnhIn the rhythmically active pyloric circuit of the spiny lobster, the pyloric dilator (PD) neurons are members of the pacemaker group of neurons that make inhibitory synapses onto the follower lateral pyloric (LP) neuron. The LP neuron, in turn, makes a depressing inhibitory synapse to the PD neurons, providing the sole inhibitory feedback from the pyloric network to its pacemakers. This study investigates the dynamic interaction between the pyloric cycle period, the two types of neurons, and the feedback synapse in biologically realistic conditions. When the rhythm period was changed, the membrane potential waveform of the LP neuron was affected with a consistent pattern. These changes in the LP neuron waveform directly affected the dynamics of the LP to PD synapse and caused the postsynaptic potential (PSP) in the PD neurons to both peak earlier in phase and become larger in amplitude. Using an artificial synapse implemented in dynamic clamp, we show that when the LP to PD PSP occurred early in phase, it acted to speed up the pyloric rhythm, and larger PSPs also strengthened this trend. Together, these results indicate that interactions between these two types of neurons can dynamically change in response to increases in the rhythm period, and this dynamic change provides a negative feedback to the pacemaker group that could work to stabilize the rhythm period.'jdCenter for Molecular and Behavioral Neuroscience, Rutgers University, Newark, New Jersey 07102, USA.Mamiya, A. Nadim, F. 1529-2401 Journal Articlee J Neurosci:3Animals Biological Clocks/*physiology Digestive System/innervation Excitatory Postsynaptic Potentials/physiology Feedback/physiology In Vitro Models, Neurological Neural Inhibition/*physiology Neurons/*physiology Palinuridae/*physiology *Periodicity Research Support, U.S. Gov't, P.H.S. Synapses/*physiologyLlehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15175383o84164080("Mancillas, J. R. Selverston, A. I.Neuropeptide modulation of photosensitivity. II. Physiological and anatomical effects of substance P on the lateral eye of LimulusAnimal Arousal/physiology Circadian Rhythm/drug effects Dose-Response Relationship, Drug Electroretinography Eye/anatomy & histology/innervation/*physiology Female Horseshoe Crabs/*physiology *Light Male Photoreceptors/drug effects/radiation effects Substance P/*pharmacologyhF@A system of efferent substance P-like immunoreactive fibers innervates the ommatidia of the Limulus lateral eye. Thus, we tested the physiological effects of substance P on the lateral eye by measuring the electroretinogram, a population potential reflecting the photoreceptors' response to light, under different experimental conditions. Substance P had no direct effect on the photoreceptors, but it induced an increase in their responsiveness to test flashes of light. The latency, magnitude, and duration of this reversible modulatory effect was dose-dependent. The lateral eye displays an endogenous circadian rhythm in its responsiveness to light. Application of exogenous substance P in the daytime causes an immediate rise as well as an increase in the nocturnal peak, while injection of one of its antagonists (D-Pro2, D-Phe7, D-Trp9 substance P) in the afternoon retards the normal rise in sensitivity and reduces the nighttime levels. Passive incubation with substance P antibodies at midnight caused a drop to diurnal levels of photosensitivity. Short-term changes in photosensitivity, similar in their nature to the substance P-induced ones, were caused by arousing the subjects. Arousal had an effect on the ongoing circadian rhythm similar to that of substance P application. Thus, the substance P efferent system may regulate neural responsiveness in both a short-term, environmentally induced manner, as well as for level setting in a circadian fashion. The mechanism for substance P-induced increases in photosensitivity involves changes in ommatidial structure: contraction of distal pigment cells, resulting in an increased aperture, and contraction of the retinular cells and rhabdom, resulting in a wider diameter of the latter. These structural modifications result in a greater angle of acceptance and increased light quantum catch. J Neurosci 198443 847-59> 91132254 Hooper, S. L. Moulins, M.arlCellular and synaptic mechanisms responsible for a long-lasting restructuring of the lobster pyloric network$Animal Electric Stimulation Electrophysiology Heart/innervation Isoquinolines/diagnostic use Lobsters/*physiology Neurons, Afferent/*physiology Pylorus/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Synapses/drug effects/physiology Synaptic Transmission/physiology  1. In the lobster Palinurus vulgaris a sensory input in the lateral posterolateral nerve (lpln) of the stomatogastric nervous system (STS) is able to turn on the cardiac sac (CS) network and to induce dramatic long-lasting alterations in the output of the pyloric network. This long-lasting alteration of pyloric network output consists primarily of changes in the activity of the two neurons that innervate the muscles of the cardiopyloric valve of the stomach, with the dilator neuron (the ventricular dilator, VD) transferring from the pyloric network to the CS network and the constrictor neuron (the inferior cardiac, IC) shifting to fire earlier in the pyloric pattern. 2. The inferior ventricular (IV) neurons of the CS network make complex multiaction synaptic connections onto several pyloric neurons in a related species, Panulirus interruptus. We show that many of the short-term alterations in pyloric activity observed during CS network bursts in Palinurus are due to similar IV neuron synaptic connections. However, the long- lasting effects of lpln stimulation on pyloric output are not due to this synaptic input, because 1) direct activation of the IV neurons does not induce long-lasting changes in pyloric activity and 2) pharmacologic disconnection of this synaptic input does not abolish lpln stimulation's long-lasting effects. Lpln stimulation therefore activates two different neuronal inputs to the pyloric network. 3. The transfer of the VD neuron from the pyloric to the CS network is the result of the concerted actions of these two inputs. Lpln stimulation turns on the CS network, and the IV neurons of the CS network excite the VD neuron and ensure it fires with the CS network. The second neuronal input (that not involving known CS network neurons) abolishes in a long-lasting fashion the VD neuron regenerative (plateau) properties, and thus suppresses the ability of the VD neuron to participate in the pyloric rhythmic pattern between CS network bursts. 4. Experimental manipulation of VD neuron activity can both mimic and reverse the effects of lpln stimulation on the IC neuron. The changes in IC neuron activity are therefore not due to direct lpln-activated synaptic input onto the IC neuron, but instead are indirect "network" effects arising from the changes in VD neuron activity.J Neurophysiol 19906451574-8991132253,&Hooper, S. L. Moulins, M. Nonnotte, L.^WSensory input induces long-lasting changes in the output of the lobster pyloric networktAnimal Electric Stimulation Electrophysiology Female Lobsters/*physiology Male Microscopy, Electron Neurons, Afferent/*physiology/ultrastructure Physical Stimulation Pylorus/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.1. A long-lasting restructuring of the pyloric neural network of the lobster stomatogastric nervous system (STS) by a multisynaptic sensory afferent is described. This restructuring can be obtained either by mechanical stimulation of the pyloric region of the stomach or by brief high-frequency electrical stimulation of a nerve that innervates this region, the lateral posterolateral nerve (lpln). Electron microscopy shows that this nerve contains several thousand very small fibers (approximately 0.3 microns diam), the activation of some subset of which is responsible for the effects of lpln stimulation. 2. These stimulation paradigms result in both short-duration changes in pyloric activity and modulatory effects long outlasting the stimulus end. The long-lasting changes include the cessation of rhythmic ventricular dilator (VD) and lateral pyloric (LP) neuron activity, and thus result in a reduced pyloric pattern in which only the pyloric dilator (PD), inferior cardiac (IC), anterior burster (AB), and pyloric (PY) neurons are active. 3. Tonic low-frequency lpln stimulation, alternatively, results in the VD neuron rhythmically firing long spike bursts with a cycle frequency much slower than that of the pyloric network while an otherwise complete pyloric pattern continues. In this new bursting pattern the VD neuron fires exclusively with another STS neural network, the cardiac sac (CS) network, and thus functionally "switches" from the pyloric to the CS network. This switch of the VD neuron from the pyloric to the CS network also occurs when the CS network is spontaneously active. 4. Our results thus demonstrate that sensory input can provoke a long-lasting modification of the functional configuration of a rhythmic neural network. They further extend the concept of flexibility in nervous systems by showing that individual neurons can belong to more than one neural network, "switching" from one to another in response to sensory input or spontaneous central nervous activity.J Neurophysiol 19906451555-7397401426 Hooper, S. L.ongPhase maintenance in the pyloric pattern of the lobster (Panulirus interruptus) stomatogastric ganglionoAnimal Female Ganglia, Autonomic/*physiology Gastrointestinal System/*physiology Lobsters/*physiology Male *Neural Networks (Computer) Pylorus/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S.The extent to which individual neural networks can produce phase- constant motor patterns as cycle frequency is altered has not been studied extensively. I investigated this issue in the well-defined, rhythmic pyloric neural network. When pyloric cycle frequency is altered three- to fivefold, pyloric inter-neuronal delays shift by hundreds to thousands of msec, and all pyloric pattern elements show strong phase maintenance. The experimental paradigm used is unlikely to activate exogenous inputs to the network, and these delay changes are thus likely to arise from phase-compensatory mechanisms intrinsic to the network. Pyloric inter-neuronal delays depend on the time constants of the network's synapses and of the membrane properties of its neurons. The observed delay shifts thus suggest that, in response to changes in overall cycle frequency, these constants vary so as to maintain pattern phasing.J Comput Neurosci 199743191-205p x90331030*$Johnson, B. R. Harris-Warrick, R. M.b[Aminergic modulation of graded synaptic transmission in the lobster stomatogastric ganglionad]Action Potentials Animal Dopamine/pharmacology Electric Conductivity Ganglia/*physiology In Vitro Lobsters Membrane Potentials/drug effects Neurons/drug effects/*physiology Octopamine/pharmacology Serotonin/pharmacology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/drug effects/*physiology *Synaptic Transmission/drug effectsi@:Graded chemical synaptic transmission is important for establishing the motor patterns produced by the pyloric central pattern generator (CPG) circuit of the lobster stomatogastric ganglion (Raper, 1979; Anderson and Barker, 1981; Graubard et al., 1983). We examined the modulatory effects of the amines dopamine (DA), serotonin (5-HT), and octopamine (Oct) on graded synaptic transmission at all the central chemical synapses made by the pyloric dilator (PD) neuron onto its follower cells, using synaptic input-output curves measured from cell somata. DA strongly reduced the graded synaptic strength at all the PD synapses. DA reduction of chemical synaptic strength from PD onto the inferior cardiac (IC) neuron could change the sign of synaptic interaction between these 2 cells from inhibitory to excitatory by uncovering a weak electrical connection. 5-HT had weaker and more variable effects, reducing graded synaptic strength from the PD onto the lateral pyloric and pyloric neurons and enhancing the weak synapse from the PD to the IC cell. Oct strongly enhanced the graded synaptic strength at all the PD central synapses. Oct enhancement of graded synaptic strength between the PD and IC cells could also change the sign of the interaction: weak, excitatory electrical coupling, which was sometimes dominant before Oct, was masked by the enhanced chemical inhibitory interaction during Oct application. Measurements of electrical coupling between 2 PD cells and between 2 postsynaptic cells suggest that Oct does not change the input resistance of these cells and may act directly at the PD synapses. The effects of DA and 5-HT are most easily explained by their general reductions in pre- and postsynaptic input resistance. DA, 5-HT, and Oct each produce a distinct pyloric motor pattern (Flamm and Harris-Warrick, 1986a). These amine-induced motor patterns may be explained by the unique actions of each amine on the intrinsic membrane properties of different pyloric CPG neurons (Flamm and Harris-Warrick, 1986b) and by modulation of graded synaptic transmission between the pyloric neurons. J Neurosci 19901072066-769126871760Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.d^Temperature sensitivity of graded synaptic transmission in the lobster stomatogastric ganglionAction Potentials Animal Ganglia/cytology/*physiology Lobsters Motor Neurons/physiology Neurons/physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*physiology Synaptic Transmission/*physiology TemperatureOWe examined the temperature sensitivity of graded chemical synaptic strength within the pyloric circuit of the spiny lobster stomatogastric ganglion. Cooling from 20.4 degrees C to 11.3 degrees C reduced the graded synaptic potential (GSP) amplitude at all six pyloric synapses tested. Cooling appeared to reduce the slope of the linear part of the input-output curve at three of these synapses, and did not significantly alter the threshold for transmitter release at any synapses. Pairs of neurons with a presynaptic pyloric dilator (PD) cell showed reductions in graded synaptic strength at 16.5 degrees C but those with presynaptic lateral pyloric (LP) or ventral dilator (VD) cells did not. A generalized decrease in input resistance is not responsible for the reduced GSP amplitude upon cooling, as determined by input resistance, action potential amplitude and electrical coupling measurements. We conclude that cooling reduces graded chemical strength by a direct synaptic action. Since the PD and VD cells use the same transmitter and act on some of the same postsynaptic cells, their differential sensitivity to cooling further suggests a presynaptic site of action. The temperature range used in our experiments encompasses the range that the animal normally encounters in nature. Thus, the relative importance of graded synaptic interactions in generating the pyloric motor rhythm may vary with transient changes in temperature. J Exp Biol 1991 156 267-85 Johnson, B.R. Hooper, S.Li 19922,Overview of thestomatogastric nervous system BDynamic Biological Networks: The Stomatogastric Nervous System  Cambridge, MA  MIT PressS 1-30v ^98204977 Hurley, L. M. Graubard, K.\VPharmacologically and functionally distinct calcium currents of stomatogastric neuronsVPAnimal Calcium Channel Blockers/*pharmacology Cells, Cultured *Crabs Ganglia, Invertebrate/cytology/*drug effects Male Membrane Potentials/drug effects Neuromuscular Junction/drug effects Neurons/*drug effects Patch-Clamp Techniques Stomach/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.@:Previous studies have suggested the presence of different types of calcium channels in different regions of stomatogastric neurons. We sought to pharmacologically separate these calcium channel types. We used two different preparations from different regions of stomatogastric neurons to screen a range of selective calcium channel blockers. The two preparations were isolated cell bodies in culture, in which calcium current was measured directly, and isolated neuromuscular junction, in which synaptic transmission was the indirect assay for presynaptic calcium influx. The selective blockers were two different dihydropyridines, omega-Agatoxin IVA, and omega-Conotoxin GVIA. Cultured cell bodies possessed both high-threshold calcium current and calcium-activated outward current, similar to intact neurons. The calcium current had transient and maintained components, but both components had the same voltage dependence of activation and inactivation. Dihydropyridines at >/=10 microM blocked both high- threshold calcium current and calcium-activated outward current. Nanomolar doses of omega-Agatoxin IVA did not block calcium current, but micromolar doses did. omega-Conotoxin GVIA did not block either current. In contrast, at the neuromuscular junction, dihydropyridines reduced the amplitude of postsynaptic potentials by only a modest amount, whereas omega-Agatoxin IVA at doses as low as 64 nM reduced the amplitude of postsynaptic potentials almost entirely. These effects were presynaptic. omega-Conotoxin GVIA did not change the amplitude of postsynaptic potentials. The different pharmacological profiles of the two isolated preparations suggest that there are at least two different types of calcium channel in stomatogastric neurons and that omega- Agatoxin IVA and dihydropridines can be used to pharmacologically distinguish them.J Neurophysiol 1998794i2070-81 Icely, J.D. Nott, J.A. 1984sOn the morphology and fine structure of the alimentary canal of Corophium volutator (Pallus) (Crustacea: Amphipoda)s@SPhil Trans Roy Soc B 306b 1126 49-78if_http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.cob.org.uk/JEB/191/1/jeb9309.html05$Jackel, C. Krenz, W. Nagy, F. VPBicuculline/Baclofen-Insensitive Gaba Response in Crustacean Neurones in CulturevpNeurones were dissociated from thoracic ganglia of embryonic and adult lobsters and kept in primary culture. When gamma-aminobutyric acid (GABA) was applied by pressure ejection, depolarizing or hyperpolarizing responses were produced, depending on the membrane potential. They were accompanied by an increase in membrane conductance. When they were present, action potential firing was inhibited. The pharmacological profile and ionic mechanism of GABA- evoked current were investigated under voltage-clamp with the whole- cell patch-clamp technique. The reversal potential of GABA-evoked current depended on the intracellular and extracellular Cl- concentration but not on extracellular Na+ and K+. Blockade of Ca2+ channels by Mn2+ was also without effect. The GABA-evoked current was mimicked by application of the GABAA agonists muscimol and isoguvacine with an order of potency muscimol>GABA>isoguvacine. cis-4-aminocrotonic acid (CACA), a folded and conformationally restricted GABA analogue, supposed to be diagnostic for the vertebrate GABAC receptor, also induced a bicuculline-resistant chloride current, although with a potency about 10 times lower than that of GABA. The GABA-evoked current was largely blocked by picrotoxin, but was insensitive to the GABAA antagonists bicuculline, bicuculline methiodide and SR 95531 at concentrations of up to 100 µmol l-1. Diazepam and phenobarbital did not exert modulatory effects. The GABAB antagonist phaclophen did not affect the GABA-induced current, while the GABAB agonists baclophen and 3-aminopropylphosphonic acid (3-APA) never evoked any response. Our results suggest that lobster thoracic neurones in culture express a chloride-conducting GABA-receptor channel which conforms to neither the GABAA nor the GABAB types of vertebrates but shows a pharmacology close to that of the novel GABAC receptor described in the vertebrate retina. 1994 J Exp Biol 1911 167-93 Using Smart Source Parsing76116225"Jahromi, S. S. Govind, C. K.LFUltrastructural diversity in motor units of crustacean stomach musclesAnimal Crabs/*anatomy & histology/physiology Membrane Potentials Muscle Contraction Muscle, Smooth/physiology/*ultrastructure Stomach/physiology/ultrastructure Synapses/physiologyrThe physiological and ultrastructural properties of muscle fiber.s comprising three motor units in the gastric mill of blue crabs are described. In their contractile properties muscle fibers in all motor units are similar and resemble the slow type fibers in crustacean limb muscles. The majority of fibers generate large excitatory post-synaptic potentials which do not facilitate strongly. Structurally two types of fibers are found. The one type has long sarcomeres (greater than 6 mum), thin to thick myofilament ratios of 5-6:1 and diads located near the ends of the A-band. The other type has shorter sarcomeres (less than 6 mum), thin to thick myofilament ratios of 3:1 and diads located at mid sarcomere level. Both types of fibers occur within a single motor unit and this differs from the vertebrate situation. Furthermore, the finding of fibers with a low thin to thick myofilament ratio of 3:1 demonstrates that they are not exclusive to fast type crustacean muscle but also occur in slow stomach muscles.Cell Tissue Res 1976 1662 159-66Johannen, K.C. 1991HBRhythmic motor patterns and their modulation in the intact lobsterBiology Maine Bowdoin College B.A. X `9606329760Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.zDistributed amine modulation of graded chemical transmission in the pyloric network of the lobster stomatogastric ganglionAnalysis of Variance Animal Biogenic Amine Neurotransmitters/*physiology Dopamine/physiology Ganglia, Invertebrate/cytology/*physiology In Vitro Lobsters/*physiology Membrane Potentials/drug effects/physiology Microelectrodes Neurons/*physiology Octopamine/physiology Pylorus/innervation/physiology Serotonin/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/drug effects/physiology Synaptic Transmission/*physiology Tetrodotoxin/pharmacology j d1. In the pyloric network of the lobster stomatogastric ganglion, graded synapses organize the network output. The amines dopamine (DA), serotonin, and octopamine each elicit a distinctive motor pattern from a quiescent pyloric network. We have examined the effects of these amines on the graded synaptic strengths between the six major types of neurons of this network to understand how amine modulation of synaptic strength contributes to the amine-induced motor patterns. Here we tested amine affects at 10 different graded chemical synapses of the pyloric network. We show that each amine has a statistically different spectrum of distributed effects across the network synapses. 2. Under our control conditions (isolated pairs of neurons, removal of modulatory input), most of the graded chemical synapses were weak and some synapses were nonfunctional. The output synapses of the ventricular dilator (VD) neuron were significantly stronger than the other synapses. 3. DA altered the synaptic strength of every graded chemical synapse. This amine strengthened the weak chemical output synapses of the anterior burster (AB), lateral pyloric (LP), and pyloric constrictor (PY) neurons and weakened (and in some cases abolished) the strong chemical output synapses of the VD neuron. The AB- ->inferior cardiac neuron (IC) and PY-->IC graded chemical synapses were nonfunctional under our control conditions; DA activated these silent synapses. 4. Serotonin enhanced the AB's output chemical synapses but weakened all the other graded chemical synapses examined. Octopamine's effects were much weaker than those of the other two amines. It enhanced the AB-->LP synapse and the LP's output synapses and weakly strengthened the AB-->PY, VD-->LP, and VD-->PY synapses. 5. The amines alter the input resistance of many of the pyloric neurons, and this could contribute to the observed changes in synaptic strength by altering passive current flow between input and output sites in the cells. However, the input resistance changes were relatively small compared with the changes in synaptic strength and cannot alone account for the synaptic modulation. In some cases the sign of the input resistance change was inconsistent with the change in synaptic strength. Thus the amines appear to modify synaptic transmission directly in this system. 6. This study completes our description of amine effects on all the graded synapses of the pyloric network. We summarize our present and earlier work to show that modulators can reconfigure the entire synaptic organization of a neural network by acting at many distributed synaptic sites.(ABSTRACT TRUNCATED AT 400 WORDS)J Neurophysiol 1995741 437-5298070655*$Johnson, B. R. Harris-Warrick, R. M.leAmine modulation of glutamate responses from pyloric motor neurons in lobster stomatogastric ganglionAcetylcholine/physiology Animal Biogenic Amine Neurotransmitters/*pharmacology Dopamine/pharmacology Ganglia, Invertebrate/drug effects Glutamic Acid/*pharmacology Iontophoresis Lobsters/*physiology Membrane Potentials/drug effects Motor Neurons/drug effects Nerve Net/drug effects Octopamine/pharmacology Pylorus/drug effects/innervation Serotonin/pharmacology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.c^XThe amines dopamine (DA), serotonin (5-HT), and octopamine (Oct) each elicit a distinctive motor pattern from a quiescent pyloric network in the lobster stomatogastric ganglion (STG). We previously have demonstrated that these amines alter the synaptic strength at multiple, distributed sites within the pyloric network that could contribute to the amine-induced motor patterns. Here, we examined the postsynaptic contribution to these changes in synaptic strength by determining how the amines modify responses of pyloric motor neurons to glutamate (Glu), one of the network transmitters, applied iontophoretically into the STG neuropil. Dopamine reduced the Glu responses of the pyloric dilator (PD), ventricular dilator (VD), and inferior cardiac (IC) neurons and enhanced the Glu responses of the lateral pyloric (LP) and pyloric constrictor (PY) neurons. The only effect of 5-HT was to reduce the Glu response of the VD neuron. Oct enhanced the Glu responses of the LP and PY neurons but did not affect the PD, VD, and IC responses. We also examined amine effects on the depolarizing responses to iontophoresed acetylcholine (ACh) in the PD and VD and found that they paralleled the amine effects on Glu responses in these neurons. This suggests that amine modulation of PD and VD responses to Glu and ACh may be explained by general changes in the ionic conductance of these neurons. We compare our results with our earlier work describing amine effects on synaptic strength and input resistance to show that amines act at both pre- and postsynaptic sites to modify graded synaptic transmission in the pyloric network.J Neurophysiol 19977863210-2112904487902 2003 AughaDopamine modulation of calcium currents in pyloric neurons of the lobster stomatogastric ganglion 631-43NGWe examined the dopamine (DA) modulation of calcium currents (ICa) that could contribute to the plasticity of the pyloric network in the lobster stomatogastric ganglion. Pyloric somata were voltage-clamped under conditions designed to block voltage-gated Na+, K+, and H currents. Depolarizing steps from -60 mV generated voltage-dependent, inward currents that appeared to originate in electrotonically distal, imperfectly clamped regions of the cell. These currents were blocked by Cd2+ and enhanced by Ba2+ but unaffected by Ni2+. Dopamine enhanced the peak ICa in the pyloric constrictor (PY), lateral pyloric (LP), and inferior cardiac (IC) neurons and reduced peak ICa in the ventricular dilator (VD), pyloric dilator (PD), and anterior burster (AB) neurons. All of these effects, except for the AB, are consistent with DA's excitation or inhibition of firing in the pyloric neurons. Enhancement of ICa in PY and LP neurons and reduction of ICa in VD and PD neurons are also consistent with DA-induced synaptic strength changes via modulation of presynaptic ICa. However, the reduction of ICa in AB suggests that DA's enhancement of AB transmitter release is not directly mediated through presynaptic ICa. ICa in PY and PD neurons was more sensitive to nifedipine block than in AB neurons. In addition, nifedipine blocked DA's effects on ICa in the PY and PD neurons but not in the AB neuron. Thus the contribution of specific calcium channel subtypes carrying the total ICa may vary between pyloric neuron classes, and DA may act on different calcium channel subtypes in the different pyloric neurons.'pjDepartment of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, USA. BRJ1@Cornell.Edu:4Johnson, B. R. Kloppenburg, P. Harris-Warrick, R. M.("22786631 0022-3077 Journal ArticleJ Neurophysiol Animal Calcium Channel Blockers/pharmacology Calcium Channels/drug effects/*physiology Dopamine/*physiology Electrophysiology Neurons/drug effects/*physiology Nifedipine/pharmacology Palinuridae Patch-Clamp Techniques Pylorus/*innervation Support, U.S. Gov't, P.H.S.lehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12904487r ,9335343960Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.leAmine modulation of electrical coupling in the pyloric network of the lobster stomatogastric ganglion  Amines/*metabolism Animal Electric Conductivity Electrophysiology Ganglia/*physiology Neural Pathways/cytology/physiology Neurons/physiology Pylorus/*innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiologys 1. The neurons of the pyloric network of the lobster (Panulirus interruptus) stomatogastric ganglion organize their rhythmic motor output using both chemical and electrical synapses. The 6 electrical synapses within this network help set the firing phases of the pyloric neurons during each rhythmic cycle. We examined the modulatory effects of the amines dopamine (DA), serotonin (5HT) and octopamine (Oct) on coupling at all the electrical synapses of the pyloric network. 2. Electrical coupling within the pacemaker group [anterior burster (AB) to pyloric dilator (PD), and PD-PD] was non-rectifying, while coupling at the other electrical synapses [AB to ventral dilator (VD), PD-VD, lateral pyloric (LP) to pyloric (PY), and PY-PY] was rectifying. 3. Dopamine decreased or increased the coupling strength of all the pyloric electrical synapses: the sign of the effect depended upon which neuron was the target of current injection. For example, DA decreased AB-->PD coupling (i.e., when current was injected into the AB) but increased coupling in the other direction, PD-->AB. Dopamine decreased AB to VD coupling when current was injected into either neuron. Serotonin also had mixed effects; it enhanced PD-->AB coupling but decreased AB to VD and PD to VD coupling in both directions. Octopamine's only effect was to reduce PD-->VD coupling. 4. Dopamine increased the input resistance of the AB neuron but decreased the input resistance of the PD and VD neurons. Serotonin reduced the input resistance of the VD and PY neurons, while Oct did not significantly change the input resistance of any pyloric neuron. 5. The characteristic modulation of electrical coupling by each amine may contribute to the unique motor pattern that DA, 5HT and Oct each elicit from the pyloric motor network. 1993J Comp Physiol [A] 172t6r 715-32 Using Smart Source Parsing9406157260Johnson, B. R. Peck, J. H. Harris-Warrick, R. M.JDDopamine induces sign reversal at mixed chemical-electrical synapses Animal Dopamine/*pharmacology Electrochemistry Ganglia, Invertebrate/drug effects/metabolism/physiology Lobsters Neurons/physiology Pylorus/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*drug effects/metabolism/*physiologyeA mixed chemical/electrical synapse can generate variable output when the strength of each synaptic component is modulated. At mixed synapses of the lobster pyloric network, the chemical component is inhibitory. Without neuromodulation, the chemical component is weak or absent and the electrical component often dominates. Dopamine reverses the sign of these mixed synaptic interactions by a reduction in the strength of electrical coupling and an enhancement of chemical inhibition, including activation of silent chemical synapses. Sign reversal at mixed synapses by neuromodulators may contribute to functional rewiring of neural networks. Brain Res 1993 6251 159-64  LFJorge-Rivera, J. C. Sen, K. Birmingham, J. T. Abbott, L. F. Marder, E.XQTemporal dynamics of convergent modulation at a crustacean neuromuscular junction ZSAnimal Crustacea Electric Stimulation Evoked Potentials/drug effects/physiology Male Motor Neurons/drug effects/physiology Muscle Contraction/drug effects/physiology Muscle Relaxation/drug effects/physiology Neuromuscular Junction/drug effects/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.At least 10 different substances modulate the amplitude of nerve-evoked contractions of the gastric mill 4 (gm4) muscle of the crab, Cancer borealis. Serotonin, dopamine, octopamine, proctolin, red pigment concentrating hormone, crustacean cardioactive peptide, TNRNFLRFamide, and SDRNFLRFamide increased and -allatostatin-3 and histamine decreased the amplitude of nerve-evoked contractions. Modulator efficacy was frequency dependent; TNRNFLRFamide, proctolin, and allatostatin-3 were more effective when the motor neuron was stimulated at 10 Hz than at 40 Hz, whereas the reverse was true for dopamine and serotonin. The modulators that were most effective at high stimulus frequencies produced a significant decrease in muscle relaxation time; those that were most effective at low stimulus frequencies produced modest increases in relaxation time. Thus modulator actions that appear redundant when examined only at one stimulus frequency are differentiated when a range of stimulus dynamics is studied. The effects of TNRNFLRFamide, serotonin, proctolin, dopamine, and - allatostatin-3 on the amplitude and facilitation of nerve-evoked excitatory junctional potentials (EJPs) in the gm4 and gastric mill 6 (gm6) muscles were compared. The EJPs in gm4 have a large initial amplitude and show relatively little facilitation, whereas the EJPs in gm6 have a small initial amplitude and show considerable facilitation. Modulators that enhanced contractions also enhanced EJP amplitude; - allatostatin-3 reduced EJP amplitude. The effects of these modulators on EJP amplitude were modest and showed no significant frequency dependence. This suggests that the frequency dependence of modulator action on contraction results from effects on excitation-contraction coupling. The modulators affected facilitation at these junctions in a manner consistent with a change in release probability. They produced a change in facilitation that is inversely related to their action on EJP amplitude.'b\Volen Center and Biology Department, Brandeis University, Waltham, Massachusetts 02454, USA.9819263http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=9819263 http://jn.physiology.org/cgi/content/full/80/5/2559J Neurophysiol 19988052559-70. Katz, P.S. 1989b[Motor pattern modulation by serotonergic sensory cells in the stomatogastric nervous system  Ithaca, NY Cornell University Ph.D.\ |ne/pharmacology89361606(!Katz, P. S. Harris-Warrick, R. M.aSerotonergic/cholinergic muscle receptor cells in the crab stomatogastric nervous system. II. Rapid nicotinic and prolonged modulatory effects on neurons in the stomatogastric ganglion*#Animal Crabs/*physiology Ganglia/*cytology/drug effects/physiology Gastrointestinal System/*innervation Muscarine/*antagonists & inhibitors Neurons, Afferent/drug effects/*physiology Nicotine/*antagonists & inhibitors Serotonin/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.( " 1. The gastropyloric receptor (GPR) cells, which are described in the preceding paper, are a set of proprioceptive cells in the crabs Cancer borealis and Cancer irroratus that contain serotonin (5- hydroxytryptamine, 5-HT) and choline acetyltransferase. These cells have a variety of synaptic effects on cells in the stomatogastric ganglion (STG). We used pharmacologic methods to distinguish the effects that were due to acetylcholine (ACh) from those that could be due to serotonin. 2. The GPR cells evoke excitatory postsynaptic potentials (EPSPs) in two gastric mill motor neurons [lateral and dorsal gastric (LG and DG)] in the stomatogastric ganglion. The EPSPs exhibit nicotinic pharmacology, indicating that they may be due to the release of ACh from the GPR cells. 3. A train of GPR action potentials induces plateau potential properties in the DG motor neuron. This plateau potential induction is not blocked by nicotinic or muscarinic antagonists, suggesting it might be due to serotonin released from the GPR cells. Bath-applied serotonin induces a tonic depolarization of DG with high-intensity spiking. 4. In the accompanying paper, it is shown that DG-evoked muscle contraction leads to the excitation of GPR2 through mechanical coupling of the muscles. Because GPR2 also excites DG, a positive feedback loop exists between GPR2 and DG. This reflex loop may be involved in the control of the medial tooth of the gastric mill. 5. GPR stimulation initiates or enhances rhythmic pyloric cycling. This is due at least in part to a direct enhancement of bursting in the pyloric dilator/anterior burster (PD/AB) pacemaker cell group and can outlast the period of GPR stimulation by up to 1 min. GPR- induced PD burst enhancement continues in the presence of nicotinic and muscarinic antagonists, indicating that the effect is probably not due to the release of ACh. Bath application of serotonin mimicks the neuromodulatory effect of GPR stimulation on the PD/AB group by inducing or enhancing bursting. 6. Thus the GPR cells elicit at least three different synaptic actions in the stomatogastric ganglion: 1) classical, fast nicotinic cholinergic EPSPs that may be important for reflex functions in the gastric mill; 2) noncholinergic, cycle-by-cycle plateau potential induction that might be critical for the timing and operation of the gastric mill, and 3) prolonged, noncholinergic burst enhancement in pyloric neurons that is mimicked by serotonin, lasts many cycles, and may act to assure that the pyloric central pattern generator (CPG) is activated and cycling strongly.J Neurophysiol 1989622 571-81&Katz, P.S. Harris-Warrick, R.M. 1989A new role for proprioceptive geedback to CPGS: Neuromodulation by serotonergic/cholinergic mechanosendory afferents to the stomatogastric ganglion of crabs 0)Erber, J. Menzel, R. Pfluger, H. Todt, D.o$Neural Mechanisms of Behavior  Stuttgart Georg Thieme Verlag 229  ne/*physiology Jones, B.R. Hartline, D.K. 1991NHUnusual properties of outward currents in lobster stomatogastric neurons Biophys J59 26797114814$Jorge-Rivera, J. C. Marder, E.piTNRNFLRFamide and SDRNFLRFamide modulate muscles of the stomatogastric system of the crab Cancer borealisrjcAnimal Crabs/*physiology Evoked Potentials/physiology Gastrointestinal System/innervation/*physiology Invertebrate Hormones/*physiology Male Microelectrodes Motor Neurons/physiology Muscle Contraction/physiology Muscles/innervation/*physiology Neuromuscular Junction/physiology Neuropeptides/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.gThe effects of the extended FLRFamide-like peptides, TNRNFLRFamide and SDRNFLRFamide, were studied on the stomach musculature of the crab Cancer borealis. Peptide-induced modulation of nerve-evoked contractions was used to screen muscles. All but 2 of the 17 muscles tested were modulated by the peptides. In several muscles of the pyloric region, peptides induced long-lasting myogenic activity. In other muscles, the peptides increased the amplitude of nerve-evoked contractions, excitatory junctional potentials, and excitatory junctional currents, but produced no apparent change in the input resistance of the muscle fibers. The threshold concentration was 10(- 10) M for TNRNFLRFamide and between 10(-9) M to 10(-8) M for SDRNFLRFamide. The absence of direct peptide-containing innervation to these muscles and the wide-spread sensitivity of these muscles to the peptides suggest that TNRNFLRFamide and SDRNFLRFamide may be released from neurosecretory structures to modulate stomatogastric musculature hormonally. We speculate that hormonally released peptide will be crucial for maintaining appreciable muscle contraction in response to low-frequency and low-intensity motor discharge. J Comp Physiol [A] 1996 179(6o 741-51 Llf`http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.cob.org.uk/JEB/200/23/jeb1087.html98028703$Jorge-Rivera, J. Marder, Y. E.b\Allatostatin decreases stomatogastric neuromuscular transmission in the crab Cancer borealisAcetylcholine/pharmacology/physiology Animal Crabs/*drug effects/*physiology Glutamic Acid/pharmacology/physiology Insect Hormones/*pharmacology/physiology Male Muscle Contraction/drug effects Neuromuscular Junction/drug effects/physiology Neuropeptides/*pharmacology/physiology Stomach/drug effects/innervation Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synaptic Transmission/drug effects~xThe effects of insect allatostatins (ASTs) 1-4 were studied on the stomach musculature of the crab Cancer borealis. Of these, Diploptera- allatostatin 3 (D-AST-3) was the most effective. D-AST-3 (10(-6 )mol l- 1) reduced the amplitude of nerve-evoked contractions, excitatory junctional potentials and excitatory junctional currents at both cholinergic and glutamatergic neuromuscular junctions. Muscle fiber responses to ionophoretic applications of both acetylcholine and glutamate were reduced by the peptide, but D-AST-3 produced no apparent change in the input resistance of the muscle fiber. D-AST-3 reduced the amplitude of muscle contractures evoked by both acetylcholine and glutamate, but had no effect on contractures induced by a high [K+]. These data suggest that D-AST-3 decreases the postsynaptic actions of both neurally released acetylcholine and glutamate. Because an AST-like peptide is found in peripheral sensory neurons that innervate stomatogastric muscles and in the pericardial organs, we suggest that an AST-like peptide may play a role in controlling the gain of the excitatory neuromuscular junctions in the stomach. J Exp Biol 1997 200c Pt 23d2937-46y :{Neuronal Plasticity$Neuronal Plasti893616054-Katz, P. S. Eigg, M. H. Harris-Warrick, R. M.WSerotonergic/cholinergic muscle receptor cells in the crab stomatogastric nervous system. I. Identification and characterization of the gastropyloric receptor cellsAcetylcholine/*physiology Animal Crabs/*physiology Ganglia/*cytology/physiology Gastrointestinal System/*innervation Neurons, Afferent/*physiology Serotonin/*physiology Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. 1. Serotonin (5-hydroxytryptamine) immunohistochemistry was used to locate and anatomically describe a set of four muscle receptor cells in the stomatogastric nervous system of the crabs Cancer borealis and Cancer irroratus. We found that these sensory cells, which we named gastropyloric receptor (GPR) cells, are the sole source of serotonergic inputs to the stomatogastric ganglion (STG) in these species. Thus any endogenous serotonergic modulation of the central pattern generators (CPGs) in the STG must be afferent and not descending from other ganglia. 2. There are two bilateral pairs of GPR cells. Each pair consists of two cell types (GPR1 and GPR2) based on differences in muscle innervation and physiological response characteristics. GPR2 responds in a mostly tonic fashion to increases in muscle tension caused by passive stretch or motor neuron-evoked contraction, whereas GPR1 responds more phasically and adapts more rapidly. Both GPR cell types project to the midline STG and terminate in each of the bilaterally paired commissural ganglia (COGs). 3. The GPR cells have sensory endings unlike any described for other muscle receptor cells: the terminals enter invaginations of the muscle surface and end near the z-bands of the muscle. These novel structures may be involved in the sensory transduction process. 4. The GPR cells may contain acetylcholine in addition to serotonin, as indicated by the presence of choline acetyltransferase (ChAT) in GPR2 (Table 1) and probably GPR1 as well. 5. The GPR cells have no direct effect on muscle properties or neuromuscular transmission: excitatory junctional potential (EJP) amplitude and motor neuron-evoked tension are unaffected by GPR stimulation. However, very low concentrations of exogenously applied serotonin do cause an increase in motor neuron-evoked muscle tension, probably reflecting a hormonal action of the amine. 6. The activity of GPR2 was monitored in a semi-intact preparation. GPR2 is active in phase with normal movements of the gastric mill. GPR2 is also capable of endogenous rhythmic activity. This indicates that even in the absence of mechanical stimulation, the GPR cells may still provide patterned input to the CPGs in the STG. 7. The GPR cells are proprioceptive cells that use serotonin and acetylcholine as cotransmitters. It is important to characterize these cells to understand the role of serotonergic modulation in the production of motor programs by stomatogastric CPGs.J Neurophysiol 1989622 558-70 o:p}(#Serotonin/*isolation & purificationSerotonin/*pharmacologySerotonin/*physiologySerotonin/*secretionSerotonin/analysis$ Serotonin/immunology/*physiologySerotonin/metabolismSerotonin/pharmacology("Serotonin/pharmacology/*physiologySerotonin/physiologyShrimp/*physiology($Signal Processing, Computer-Assisted$Signal Transduction/*physiology$ Signal Transduction/drug effects0+Signal Transduction/drug effects/physiologySmell/physiology Sodium Channels/drug effects,'Sodium Channels/drug effects/physiology Sodium Channels/physiologySodium/*physiologySodium/metabolismSodium/physiology$Somatosensory Cortex/physiologySpecies SpecificityD?Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization($Spinal Cord Injuries/physiopathologySpinal Cord/*physiologySpinal Cord/physiology StainingStaining and LabelingStimulation, ChemicalStochastic Processes StomachStomach/*innervation$Stomach/*innervation/physiologyStomach/*physiology83Stomach/anatomy & histology/innervation/*physiologyStomach/chemistry,'Stomach/cytology/innervation/physiology$ Stomach/drug effects/innervationStomach/injuriesStomach/innervation$Stomach/innervation/*physiology$Stomach/innervation/physiology,&Stomach/innervation/physiology/surgery Stomach/metabolism/physiologyStomach/physiology$!Stomach/physiology/ultrastructure("Stomatognathic System/*innervationStrontium/pharmacology$Structure-Activity Relationship4/Substance P/*analogs & derivatives/pharmacologySubstance P/*analysisSubstance P/*pharmacology4.Substance P/analogs & derivatives/pharmacologySubstance P/analysisSubtilisins/pharmacologySucrose/pharmacologySupport, Non-U.S. Gov't$Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Swimming/physiology("Synapses/*drug effects/*physiology0-Synapses/*drug effects/metabolism/*physiologySynapses/*physiology(#Synapses/*physiology/ultrastructureSynapses/*ultrastructure Synapses/chemistry/physiologySynapses/drug effects$!Synapses/drug effects/*metabolism$!Synapses/drug effects/*physiology$ Synapses/drug effects/physiologySynapses/metabolism(#Synapses/metabolism/*ultrastructureSynapses/physiology(#Synapses/physiology/*ultrastructure("Synapses/physiology/ultrastructureSynapsins/analysisSynaptic depressionsynaptic dynamics$Synaptic Membranes/drug effectsSynaptic Transmission(#Synaptic Transmission/*drug effects$!Synaptic Transmission/*physiology("Synaptic Transmission/drug effects4.Synaptic Transmission/drug effects/*physiology$ Synaptic Transmission/physiologySynaptic Vesicles$!Synaptic Vesicles/*ultrastructure0+Synaptic Vesicles/secretion/*ultrastructure$ Synaptic Vesicles/ultrastructure<9Tachykinins/*analysis/isolation & purification/metabolism40Tachykinins/*metabolism/pharmacology/*physiologyTachykinins/analysis4/Tachykinins/antagonists & inhibitors/metabolismTachykinins/metabolismTachykinins/pharmacology Tannic Acid Temperature,'Tendons/*anatomy & histology/physiology$!Tetanus Toxin/genetics/metabolism,)Tetraethylammonium Compounds/pharmacology Tetrodotoxin/*pharmacologyTetrodotoxin/pharmacology(#Theophylline/*analogs & derivativesThorax/innervation Time FactorsTissue CultureTissue DistributionTissue FixationTooth/*innervation Tooth/innervation/physiologyTooth/physiology("Transcription, Genetic/*physiologyTrimethaphan/pharmacologyTubocurarine/pharmacologyTubulin/metabolism$!Tyrosine 3-Monooxygenase/analysis4/Tyrosine 3-Monooxygenase/immunology/*metabolism(#Tyrosine 3-Monooxygenase/metabolismVertebrates/physiology Wave formWeight-Bearing Xenopus Xenopus/genetics/metabolismtic dynamicsphase maintenance4-Nadim, F. Manor, Y. Nusbaum, M. P. Marder, E.  1998D>Frequency regulation of a slow rhythm by a fast periodic input J Neurosci18135053-67i98299896Many nervous systems contain rhythmically active subnetworks that interact despite oscillating at widely different frequencies. The stomatogastric nervous system of the crab Cancer borealis produces a rapid pyloric rhythm and a considerably slower gastric mill rhythm. We construct and analyze a conductance-based compartmental model to explore the activation of the gastric mill rhythm by the modulatory commissural neuron 1 (MCN1). This model demonstrates that the period of the MCN1-activated gastric mill rhythm, which was thought to be determined entirely by the interaction of neurons in the gastric mill network, can be strongly influenced by inhibitory synaptic input from the pacemaker neuron of the fast pyloric rhythm, the anterior burster (AB) neuron. Surprisingly, the change of the gastric mill period produced by the pyloric input to the gastric mill system can be many times larger than the period of the pyloric rhythm itself. This model illustrates several mechanisms by which a fast oscillatory neuron may control the frequency of a much slower oscillatory network. These findings suggest that it is possible to modify the slow rhythm either by direct modulation or indirectly by modulating the faster rhythm.nghttp://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/referer?http://www.jneurosci.org/cgi/content/full/18/13/50532 | 91020406(!Katz, P. S. Harris-Warrick, R. M.pLFActions of identified neuromodulatory neurons in a simple motor systemAnimal Crustacea Motor Neurons/*physiology Neurotransmitters/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.Recent work on neurons that release slow neuromodulators has revealed important generalities about the roles played by neuromodulation in motor systems. Activity of these cells can affect the cellular and synaptic properties of central pattern generating circuits, orchestrating new variations of motor patterns and sometimes coordinating their outputs with other motor patterns. Many modulatory neurons use multiple transmitters to evoke both fast and slow synaptic responses of various types in different target cells. Some modulatory cells can have a mediating as well as a modulating role, simultaneously acting as sensory neurons or components of another pattern generating circuit.cTrends Neuroscir 1990139e 367-7390237878(!Katz, P. S. Harris-Warrick, R. M. xrNeuromodulation of the crab pyloric central pattern generator by serotonergic/cholinergic proprioceptive afferentsAnimal Brain/*physiology Crabs/*physiology Electric Stimulation Electrophysiology Motor Activity/physiology Neural Inhibition Neurons, Afferent/physiology Nicotine/metabolism Parasympathetic Nervous System/cytology/*physiology Proprioception/*physiology Pylorus/cytology/*innervation Serotonin/pharmacology/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology*#In the stomatogastric nervous system of the crab, Cancer borealis, a set of 4 serotonergic/cholinergic proprioceptive neurons, called gastropyloric receptor (GPR) cells, have effects on the pyloric motor pattern. In a semi-intact foregut preparation, the GPR cells are not activated by movements of the pyloric filter; instead they respond to the slower movements of the gastric mill (Katz et al., 1989). Thus, their activity is not synchronized to the pyloric motor pattern. However, when the GPR cells are stimulated in an in vitro preparation in a manner that resembles their normal firing pattern, they produce dramatic effects on the pyloric motor pattern. These effects include: (1) a prolonged increase in the pyloric cycle frequency, (2) a momentary pause in the motor pattern, (3) transient inhibition of some motor neurons, (4) strong excitation of other motor neurons, and (5) altered phase relationships of the different components of the motor pattern. These changes in the motor pattern are due to direct effects of the GPR cells on neurons in the pyloric central pattern generator (CPG). All of the cells in the pyloric circuit appear to receive GPR input. However, only 2 neurons receive detectable rapid nicotinic synaptic potentials. The other neurons receive only slower neuromodulatory input from GPR stimulation. The neuromodulatory effects include burst enhancement, plateau potential enhancement, excitation, and inhibition. These modulatory effects are largely mimicked by bath- applied serotonin (5-HT). Thus, primary sensory neurons can alter the production of motor patterns by a CPG through a phase-independent mechanism; these proprioceptors do not need to fire at a precise time in the cycle to be effective because their effects are mediated through the slower actions of the neuromodulator 5-HT. J Neurosci 1990105a1495-512 Katz, P.S. 1991@:Neuromodulation and the evolution of a simple motor system SINS3379-38991341572(!Katz, P. S. Harris-Warrick, R. M.tnRecruitment of crab gastric mill neurons into the pyloric motor pattern by mechanosensory afferent stimulationAcetylcholine/pharmacology Animal Crabs/*physiology Dendrites/physiology Evoked Potentials/drug effects/physiology Gastrointestinal Motility/drug effects/*physiology Microelectrodes Neurons, Afferent/drug effects/*physiology Parasympatholytics/pharmacology Physical Stimulation Picrotoxin/pharmacology Pirenzepine/pharmacology Pylorus/*innervation Recruitment (Neurology)/*physiology Scopolamine/pharmacology Serotonin/metabolism Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/physiology Tubocurarine/pharmacologyo1. The gastropyloric receptor (GPR) cells are stretch-sensitive muscle receptors in the crab stomatogastric nervous system that use both 5- hydroxytryptamine (serotonin) and acetylcholine as cotransmitters. Brief stimulation of these afferent neurons causes two gastric mill neurons to be recruited into the pyloric motor pattern. 2. The GPR cells evoke complex synaptic potentials in the lateral gastric (LG) and medial gastric (MG) motor neurons, two component neurons of the gastric mill central pattern generator. When the gastric mill is quiescent (as often happens in vivo), GPR stimulation transiently inhibits LG and MG. After this transient inhibition, these cells undergo a prolonged excitation during which they fire bursts of action potentials at a constant phase relation to the pyloric motor pattern. 3. To determine the causes for this effect, we examined the effects of GPR stimulation on these two cells and on the inferior cardiac motor neuron, which is electrically coupled to them. When GPR is stimulated, all three cells receive rapid biphasic synaptic potentials that are blocked by nicotinic antagonists, followed by a slow, prolonged depolarizing potential. 4. The slow, prolonged depolarizing potential is not blocked by nicotinic or muscarinic cholinergic antagonists but is mimicked and occluded by exogenously applied serotonin. 5. The prolonged excitation, mediated at least in part by serotonin, may be responsible for the recruitment of the gastric mill neurons into the pyloric motor pattern. Thus sensory input can directly exert prolonged modulatory effects that change the functional cellular composition of pattern-generating circuits.tJ Neurophysiol 1991656t1442-51rKatz, P.S. Tazaki, K. 1992RLComparative and evolutionary aspects of the crustacean stomatogastric system BDynamic Biological Networks: The Stomatogastric Nervous System  Cambridge, MAy  MIT Pressi221-262("Katz, P.S. Kirk, M.D. Govind, C.K. 1993yFacilitation and depression at different branches of the same motor axon: Evidence for presynaptic differences in release J Neurosci13 3075-3089k Katz, P.S. 1995^XNeuromodulation and motor pattern generation in crustacean stomatogastric nervous system Ferrell, W.R. Proske, U."Neural Control of Movements New York  Plenum press277-283aE Kopell1994F Kopell1994^ Kopell19944{ Kopell1997 Kopell19977* Kopell1998Q Kopell19999 Kopell1999 Kravitz1972( Kravitz1983 Krenz1994+ Krenz2000 Kumar1990, Kunze19760 Kushner1977 Kushner1979- Kushner1979/ Kushner1983 Kushner1987. Kushner1987 Kwan19787 Labenia2000 Lange1989 Lanning1997% Lanning1997 Lanning2000! 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Lingle1981@ Lingle1981A Lingle1982; Lingle1983< Lingle1983= Lingle1983> Lingle1983 Lingle1986 Lingle1987q Liu1996B Liu1998CLnenicka1985DLnenicka1986E LoFaro1994F LoFaro1994G Lovett1989H Lovett1990 Lubell19969 Lubics19999P Lundquist1997 Luther20012I Luther2003J MacLean2003 MacLean2003K Macmillan1976 Macmillan1976w Mahadevan2001L Mamiya2003 Mamiya2004M Mancillas1984 Manhas20044 Mann19869P Manor1997| Manor1998 Manor1998# Manor1999 Manor1999Q Manor1999 Manor1999 Manor2000N Manor2001O Manor2001 Manor2001L Manor2003 Manor2003 Manor2003 Manor2004 Manor2004 Manor2005R Marder1974 Marder1976S Marder1976 Marder1978 Marder1980 Marder1980? Marder1981@ Marder1981 Marder1982A Marder1982T Marder1982 Marder1983' Marder1984i Marder1984 Marder1984U Marder1984V Marder1984u Marder1984v Marder1984x Marder1985 Marder1986 Marder19869y Marder1986 Marder1987W Marder1987X Marder1987 Marder19888Y Marder1988 Marder19888x Marder19899Z Marder1989[ Marder1989} Marder1989~ Marder1989 Marder19899 Marder19899 Marder19899 Marder19899z Marder19909 Marder19900 Marder19909 Marder1990 Marder19900 Marder1991 Marder1991i Marder1991\ Marder1991] Marder1991^ Marder1991 Marder19911 Marder1991 Marder199118 Marder19922 Marder19922 Marder19929 Marder19929 Marder19922 Marder1992n Marder1992 Marder1992 Marder1992 Marder1992 Marder19922 Marder19929F Marder1992 Marder19939 Marder19933 Marder19935 Marder19939_ Marder1993m Marder1993p Marder1993 Marder19939G Marder1993H Marder1993_ Marder19931 Marder19931 Marder19933 Marder1994O Marder19949E Marder1994F Marder1994` Marder1994a Marder1994o Marder1994J Marder1994^ Marder19944 Marder19941 Marder199440 Marder19959K Marder19959L Marder19959l Marder1995t Marder1995 Marder1995 Marder19959 Marder1996a$ Marder1996b Marder1996q Marder1996s Marder1996D Marder1996aI Marder19966 Marder19961M Marder19977 Marder19979 Marder1997aP Marder1997c Marder1997z Marder1997{ Marder1997 Marder1997a Marder1998 Marder19981B Marder19989d Marder1998e Marder1998| Marder1998 Marder1998 Marder19988 Marder19988# Marder1999Lanning2000! Lanning2001 Lanning2002 Lanning20042 Larimer19661 Larimer1988qLaverack1969KLaverack19766 Laverack19799 Laverack197993 Le Feuvre19994 Le Feuvre2001) Le Feuvre2002k Le Moal1984[ Legeay19989LeMasson19935LeMasson1993LeMasson1993ooLeMasson1994Lengvari19996 Levi2003 Levini19959 Levini1997 Levini19977( Levini19998 Li20027 Li20039 Lingle1980: Lingle1981? Lingle1981@ Lingle1981A Lingle1982; Lingle1983< Lingle1983= Lingle1983> Lingle1983 Lingle1986̱ Lingle1987q Liu1996B Liu1998CLnenicka1985DLnenicka1986E LoFaro1994F LoFaro1994G Lovett1989H Lovett1990 Lubell19969 Lubics19999P Lundquist1997 Luther20012I Luther2003J MacLean2003K Macmillan1976w Mahadevan2001L Mamiya2003M Mancillas1984 Mann19869P Manor1997| Manor1998 Manor1998# Manor1999 Manor1999Q Manor1999 Manor1999 Manor2000N Manor2001O Manor2001 Manor2001L Manor2003 Manor2003R Marder1974 Marder1976S Marder1976̀ Marder1978́ Marder1980̂ Marder1980? Marder1981@ Marder1981̂ Marder1982A Marder1982T Marder1982 Marder1983' Marder1984i Marder1984 Marder1984U Marder1984V Marder1984u Marder1984v Marder1984x Marder1985 Marder1986 Marder19869y Marder1986 Marder1987W Marder1987X Marder1987̣ Marder19888Y Marder1988 Marder19888x Marder19899Z Marder1989[ Marder1989} Marder1989~ Marder1989 Marder19899 Marder19899 Marder19899z Marder19909 Marder19900 Marder19909 Marder1990 Marder1991 Marder1991i Marder1991\ Marder1991] Marder1991^ Marder1991̚ Marder19911 Marder19918 Marder19922 Marder19922 Marder19929 Marder19929 Marder19922 Marder1992n Marder1992̇ Marder1992̉ Marder1992̊ Marder1992̠ Marder19922 Marder19929F Marder1992 Marder19939 Marder19933 Marder19935 Marder19939_ Marder1993m Marder1993p Marder1993 Marder19939G Marder1993H Marder1993_ Marder19931 Marder1994O Marder19949E Marder1994F Marder1994` Marder1994a Marder1994o Marder1994J Marder1994^ Marder199440 Marder19959K Marder19959L Marder19959l Marder1995t Marder1995 Marder1995  Marder1996a$ Marder1996b Marder1996q Marder1996s Marder1996D Marder1996aI Marder19966M Marder19977 Marder19979  Marder1997aP Marder1997c Marder1997z Marder1997{ Marder1997 Marder1998  Marder19981B Marder19989d Marder1998e Marder1998| Marder1998̃ Marder1998 Marder19988# Marder1999:vXRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=8820868Katz, P. S. Frost, W. N.HAIntrinsic neuromodulation: altering neuronal circuits from within.haAnimal Human *Instinct *Nervous System Physiology Neurons/*physiology Support, U.S. Gov't, P.H.S.sThere are two sources of neuromodulation for neuronal circuits: extrinsic inputs and intrinsic components of the circuits themselves. Extrinsic neuromodulation is known to be pervasive in nervous systems, but intrinsic neuromodulation is less recognized, despite the fact that it has now been demonstrated in sensory and neuromuscular circuits and in central pattern generators. By its nature, intrinsic neuromodulation produces local changes in neuronal computation, whereas extrinsic neuromodulation can cause global changes, often affecting many circuits simultaneously. Studies in a number of systems are defining the different properties of these two forms of neuromodulation.-'`ZDept of Neurobiology and Anatomy, University of Texas Medical School, Houston, 77030, USA.8820868dTrends Neurosci  1996192r 54-61.76230156Kehoe, J. Marder, E.HBIdentification and effects of neural transmitters in invertebratesAcetylcholine/physiology Animal Arthropods/physiology Blood Vessels/physiology Chemistry Dopamine/physiology Ganglia/physiology Gills/physiology Glutamates/physiology Heart/physiology Invertebrates/*physiology Mollusca/physiology Muscles/physiology Neurotransmitters/isolation & purification/*physiology Octopamine/physiology Serotonin/physiology Support, U.S. Gov't, P.H.S. Synapses/physiology Synaptic Transmission 1976 Annu Rev Pharmacol Toxicol16 245-68 Using Smart Source ParsingKennedy, M.B. Marder, E. 1992<6Cellular and molecular mechanisms of neural plasticity  Hall, Z.H.0)An Introduction to Molecular Neurobiology Sunderland, MA Sinauer Associates, Inc.463-495x90208342,&Kepler, T. B. Marder, E. Abbott, L. F.VPThe effect of electrical coupling on the frequency of model neuronal oscillatorsAction Potentials Biological Clocks Electric Conductivity Electrophysiology Mathematics Membrane Potentials *Models, Biological Neurons/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. *#Neurons with oscillatory properties are a common feature of the nervous system, but little is known about how neural oscillators shape the behavior of neuronal networks or how network interactions influence the properties of neural oscillators. Mathematical models are used to examine the effect of electrically coupling an oscillatory neuron to a second neuron that is either silent or tonically firing. Models of oscillatory neurons with varying degrees of complexity show that this coupling can either increase or decrease the frequency of an oscillator, depending on its membrane potential wave form, the state of the neuron to which it is coupled, and the strength of the coupling. Thus, electrical coupling provides a flexible mechanism for modifying the behavior of an oscillatory neural network.Science 1990 248 4951 83-5*$Kepler, T.B. Abbott, L.F. Marder, E. 1991VPOrder reduction for dynamical systems describing the behavior of complex neurons .(Lippmann, R.P. Moody, J.E. Touretzky, D.81Advances in Neural Information Processing Systems  San Mateo, CAw Morgan Kaufman Publisherst3 55-61a92223170,&Kepler, T. B. Abbott, L. F. Marder, E.2,Reduction of conductance-based neuron modelsMathematics Membrane Potentials *Models, Neurological *Neural Conduction Neurons/*physiology Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S.We present a scheme for systematically reducing the number of differential equations required for biophysically realistic neuron models. The techniques are general, are designed to be applicable to a large set of such models and retain in the reduced system as high a degree of fidelity to the original system as possible. As examples, we provide reductions of the Hodgkin-Huxley system and the A-current model of Connor et al. (1977).  1992 Biol Cybernt665  381-7  Using Smart Source Parsing93200204Kepler, T. B. Marder, E.JCSpike initiation and propagation on axons with slow inward currentsAction Potentials/physiology Animal Axons/*physiology Cybernetics Electric Conductivity Electric Stimulation Electrophysiology Models, Neurological Support, U.S. Gov't, P.H.S.n81We investigate spike initiation and propagation in a model axon that has a slow regenerative conductance as well as the usual Hodgkin-Huxley type sodium and potassium conductances. We study the role of slow conductance in producing repetitive firing, compute the dispersion relation for an axon with an additional slow conductance, and show that under appropriate conditions such an axon can produce a traveling zone of secondary spike initiation. This study illustrates some of the complex dynamics shown by excitable membranes with fast and slow conductances.r 1993 Biol Cyberni683D 209-14 Using Smart Source ParsingXRhttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=1708539 Kiehn, O.yb[Plateau potentials and active integration in the 'final common pathway' for motor behaviournAction Potentials/*physiology Animal Cats Decerebrate State Lampreys/physiology Motor Neurons/*physiology Neural Pathways/physiology Spinal Cord/*physiologyMost studies of vertebrate spinal motoneurones have suggested that they possess relatively simple membrane properties, causing them to behave merely as passively driven output neurones in motor behaviour. According to this concept, motoneurones passively transform the net synaptic drive from pre-motoneuronal levels into spike trains. Recent research has demonstrated a more complex picture by showing that motoneurones can express nonlinear intrinsic response properties, such as plateau potentials and endogenous oscillatory properties. This work suggests that the 'final common pathway' is actively involved in shaping motor behaviour.o'JCInstitute of Neurophysiology, Panum Institute, Copenhagen, Denmark.e1708539mTrends Neuroscig 1991142l 68-73.! l 92407593&Kiehn, O. Harris-Warrick, R. M.|uSerotonergic stretch receptors induce plateau properties in a crustacean motor neuron by a dual-conductance mechanism{Acetylcholine/pharmacology Animal Cesium/pharmacology Crabs/*physiology Electrophysiology Evoked Potentials/drug effects Mechanoreceptors/*physiology Motor Neurons/*physiology Parasympatholytics/pharmacology Serotonin/*physiology Stomach/cytology/innervation/physiology Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tetrodotoxin/pharmacologyc R L1. The mechanisms for induction of bistable plateau potential properties by a set of serotonergic/cholinergic peripheral stretch receptor cells [gastropyloric receptor (GPR) cells] were examined in the crab stomatogastric ganglion (STG) with the use of intracellular recording techniques. 2. GPR cell stimulation evoked nicotinic excitatory postsynaptic potentials (EPSPs) and induced plateau potential capability in the dorsal gastric (DG) motor neuron. The plateau potential could be triggered during a GPR train either by the summating nicotinic EPSPs or by brief intracellular current injection. After pharmacological blockade of nicotinic and muscarinic receptors, a slow depolarization in response to GPR stimulation was revealed. Prolonged plateau potentials could still be evoked after this treatment. Local application of serotonin (5-HT; 10 microM to 1 mM) mimicked the noncholinergic plateau inducing effects of GPR stimulation in the DG motor neuron. 3. The synergistic action of acetylcholine (ACh) and 5-HT was examined by stimulating the GPR cells at different frequencies (1-20 Hz). The plateau induction was present down to 2 Hz. The time to onset for triggering a plateau during a GPR train was determined by the co-released ACh. 4. The 5-HT-evoked slow depolarization persisted in tetrodotoxin (TTX; 0.1-1 microM), and the DG motor neuron could still produce a plateau potential on brief depolarization in the absence of the spike-generating mechanism. 5. In normal TTX-containing saline, the 5-HT-evoked depolarization was accompanied by a weak and variable decrease in apparent input conductance. After substituting one-half of the extracellular sodium with either Trisma-HCl or choline, the decrease in apparent input conductance became more pronounced. This decrease was converted to an increase in apparent input conductance when extracellular Ca2+ was replaced with Mg2+. 6. Under voltage-clamp conditions, local application of 5-HT caused a slow inward current of prolonged duration in DG. The current versus voltage relationship had an inverted U-shape with no apparent reversal potential in the entire voltage range investigated (-90 to -5 mV). The 5-HT-induced changes in input conductance showed a complex voltage dependence, with a conductance decrease from moderately depolarized voltages. 7. Extracellular Cs+ (2- 4 mM) caused the DG to hyperpolarize 2-4 mV from rest, whereas lowering extracellular Ca2+ caused it to depolarize 7-15 mV. The combined action of low extracellular Ca2+ and 2-4 mM Cs+ caused an almost complete block of the slow 5-HT-evoked depolarization.(ABSTRACT TRUNCATED AT 400 WORDS)J Neurophysiol 1992682m 485-9592407594&Kiehn, O. Harris-Warrick, R. M.5-HT modulation of hyperpolarization-activated inward current and calcium-dependent outward current in a crustacean motor neuronAnimal Barium/pharmacology Calcium Channels/*drug effects Cesium/pharmacology Crabs/*physiology Ganglia/cytology/drug effects Ion Channels/*drug effects Membrane Potentials/drug effects/physiology Motor Neurons/*drug effects Neural Conduction/drug effects Serotonin/*pharmacology Sodium/metabolism Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Tetraethylammonium Compounds/pharmacologyt 1. Serotonergic modulation of a hyperpolarization-activated inward current, Ih, and a calcium-dependent outward current, Io(Ca), was examined in the dorsal gastric (DG) motor neuron, with the use of intracellular recording techniques in an isolated preparation of the crab stomatogastric ganglion (STG). 2. Hyperpolarization of the membrane from rest with maintained current pulses resulted in a slow time-dependent relaxation back toward rest and a depolarizing overshoot after termination of the current pulse. In voltage clamp, hyperpolarizing commands negative to approximately -70 mV caused a slowly developing inward current, Ih, which showed no inactivation. Repolarization back to the holding potential of -50 mV revealed a slow inward tail current. 3. The reversal potential for Ih was approximately -35 mV. Raising extracellular K+ concentration ([K+]o) from 11 to 22 mM enhanced, whereas decreasing extracellular Na+ concentration ([Na+]o) reduced the amplitude of Ih. These results indicate that Ih in DG is carried by both K+ and Na+ ions. 4. Bath application of serotonin (5- HT; 10 microM) caused a marked increase in the amplitude of Ih through its active voltage ranges. 5. The time course of activation of Ih was well fitted by a single exponential function and strongly voltage dependent. 5-HT increased the rate of activation of Ih. 5-HT also slowed the rate of deactivation of the Ih tail on repolarization to -50 mV. 6. The activation curve for the conductance (Gh) underlying Ih was obtained by analyzing tail currents. 5-HT shifted the half activation for Gh from approximately -105 mV in control to -95 mV, resulting in an increase in the amplitude of Gh active at rest. 7. Two to 4 mM Cs+ abolished Ih, whereas barium (200 microM to 2 mM) had only weak suppressing effects on Ih. Concomitantly, Cs+ also blocked the 5-HT- induced inward current and conductance increase seen at voltages negative to rest. In current clamp, Cs+ caused DG to hyperpolarize 3-4 mV from rest, suggesting that Ih is partially active at rest and contributes to the resting membrane potential. 8. Depolarizing voltage commands from a holding potential of -50 mV resulted in a total outward current (Io) with an initial transient component and a sustained steady- state component. Application of 5-HT reduced both the transient and sustained components of Io. 9. Io was reduced by 10-20 mM tetraethylammonium (TEA), suggesting that it is primarily a K+ current.(ABSTRACT TRUNCATED AT 400 WORDS)J Neurophysiol 1992682496-508 lItYFMRFamide/*physiologyForskolin/*pharmacology0-Forskolin/analogs & derivatives/*pharmacology GABA Agonists/pharmacology GABA Antagonists/pharmacologyGABA/*analysis GABA/*metabolism/pharmacologyGABA/*pharmacologyGABA/*physiology GABA/analysisGABA/metabolismGABA/pharmacologyGABA/physiology40gamma-Aminobutyric Acid/*metabolism/pharmacology83Ganglia, Autonomic/*anatomy & histology/*physiology$Ganglia, Autonomic/*physiology0+Ganglia, Autonomic/cytology/*ultrastructure Ganglia, Autonomic/physiologyGanglia, Invertebrate$ Ganglia, Invertebrate/*chemistry4/Ganglia, Invertebrate/*chemistry/ultrastructure(#Ganglia, Invertebrate/*drug effects4.Ganglia, Invertebrate/*drug effects/metabolism4.Ganglia, Invertebrate/*drug effects/physiology$!Ganglia, Invertebrate/*metabolism0,Ganglia, Invertebrate/*metabolism/physiology$!Ganglia, Invertebrate/*physiologyD>Ganglia, Invertebrate/anatomy & histology/*cytology/physiology85Ganglia, Invertebrate/anatomy & histology/*physiology$Ganglia, Invertebrate/chemistry@=Ganglia, Invertebrate/chemistry/cytology/growth & development83Ganglia, Invertebrate/chemistry/cytology/physiology$Ganglia, Invertebrate/cytology0,Ganglia, Invertebrate/cytology/*drug effects0*Ganglia, Invertebrate/cytology/*metabolism0*Ganglia, Invertebrate/cytology/*physiology4.Ganglia, Invertebrate/cytology/*ultrastructure<7Ganglia, Invertebrate/cytology/drug effects/*metabolism<7Ganglia, Invertebrate/cytology/drug effects/*physiologyHBGanglia, Invertebrate/cytology/drug effects/immunology/*metabolism<6Ganglia, Invertebrate/cytology/drug effects/metabolism85Ganglia, Invertebrate/cytology/embryology/*metabolism,)Ganglia, Invertebrate/cytology/physiology("Ganglia, Invertebrate/drug effects4.Ganglia, Invertebrate/drug effects/*metabolism<9Ganglia, Invertebrate/drug effects/*metabolism/physiologyHBGanglia, Invertebrate/drug effects/enzymology/growth & development<8Ganglia, Invertebrate/drug effects/metabolism/physiology0-Ganglia, Invertebrate/drug effects/physiologyDAGanglia, Invertebrate/embryology/growth & development/*physiology0+Ganglia, Invertebrate/embryology/physiology<6Ganglia, Invertebrate/enzymology/immunology/metabolism<6Ganglia, Invertebrate/growth & development/*physiology$ Ganglia, Invertebrate/metabolism40Ganglia, Invertebrate/metabolism/*ultrastructure$ Ganglia, Invertebrate/physiology4/Ganglia, Invertebrate/physiology/ultrastructure$ Ganglia, Sympathetic/*physiology Ganglia/*analysis/metabolismGanglia/*chemistryGanglia/*cytology,)Ganglia/*cytology/drug effects/physiology Ganglia/*cytology/physiologyGanglia/*drug effects0+Ganglia/*drug effects/embryology/physiology$ Ganglia/*drug effects/metabolismGanglia/*physiology("Ganglia/*physiology/ultrastructure84Ganglia/anatomy & histology/*drug effects/physiology,'Ganglia/anatomy & histology/*physiology4/Ganglia/anatomy & histology/cytology/physiology Ganglia/chemistry/cytologyGanglia/cytology,)Ganglia/cytology/*drug effects/physiology Ganglia/cytology/*physiology Ganglia/cytology/drug effects,)Ganglia/cytology/drug effects/*physiology Ganglia/cytology/physiology$ Ganglia/drug effects/*physiology0+Ganglia/drug effects/metabolism/*physiologyGanglia/enzymologyGanglia/physiology("Ganglia/physiology/*ultrastructure$ Ganglionic Blockers/pharmacology(%Gap Junctions/drug effects/metabolism,'Gap Junctions/physiology/ultrastructure,(Gastric Emptying/drug effects/physiology Gastric Emptying/physiology("Gastrins/*isolation & purification 94132889*#Meyrand, P. Simmers, J. Moulins, M.n|vDynamic construction of a neural network from multiple pattern generators in the lobster stomatogastric nervous systemd^Animal Axonal Transport Axons/physiology Digestive System/innervation Electric Stimulation In Vitro Lobsters Models, Neurological Motor Neurons/physiology Muscle, Smooth/innervation Nerve Net/*physiology Nervous System/anatomy & histology/*physiology *Nervous System Physiology Neurons/*physiology Neurons, Afferent/physiology Support, Non-U.S. Gov'tIn the stomatogastric nervous system (STNS) of the lobster Homarus gammarus, the rhythmic discharge of a pair of identified modulatory neurons (PS cells) is able to construct de novo a functional network from neurons otherwise belonging to other functional networks. The PS interneurons are electrically coupled and possess endogenous oscillatory properties that can be activated synaptically by stimulation of an identified sensory pathway. PS neurons themselves project synaptically onto the three major neural networks (esophageal, gastric mill, and pyloric) of the STNS. When a PS is rhythmically active in vitro, either spontaneously (rarely) or in response to direct stimulation, it dramatically restructures the otherwise independent activity patterns of all three target networks. This functional reconfiguration elicited by a single cell does not rely on changes in neuronal allegiance to pre-existing circuits, or on a simple merger of these different circuits. Rather, PS is responsible for the creation of an entirely new motor rhythm in that, via its widespread synaptic connections, the interneuron is able to subjugate the ongoing activity of the three STNS circuits and selectively appropriate individual elements to its own intrinsic rhythm. In addition, PS excites motor neurons that innervate dilator muscles of a valve situated between the esophagus and the stomach. The reorganization of the regional foregut motor rhythms by the interneuron is therefore coordinated to the opening of this valve, which itself carries sensory receptors that have been found to activate bursting in PS. Our data suggest that the role of PS in massively restructuring stomatogastric output is to generate a unique motor pattern appropriate for swallowing-like behavior. In a wider context, moreover, the results demonstrate that a neural network may not exist as a predefined entity within the CNS, but may be dynamically assembled according to changing behavioral circumstances. J Neurosci 1994142h 630-44*#Meyrand, P. Simmers, J. Moulins, M. 1994JCModulation and specification of behavior at the small circuit level $Greenspan, R.J. Kyriacou, C.P.60Flexibility and Constraint in Behavioral Systems New York John Wiley & Sons165-176u%#$" rZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=11165800?B;Kiehn, O. Kjaerulff, O. Tresch, M. C. Harris-Warrick, R. M.bzContributions of intrinsic motor neuron properties to the production of rhythmic motor output in the mammalian spinal cord.(Animal Anterior Horn Cells/drug effects/*growth & development/physiology Gap Junctions/drug effects/metabolism Ion Channels/drug effects/metabolism Membrane Potentials/drug effects/*physiology Movement/*physiology Neural Inhibition/drug effects/physiology Periodicity Rats Support, Non-U.S. Gov'tXRMotor neurons are endowed with intrinsic and conditional membrane properties that may shape the final motor output. In the first half of this paper we present data on the contribution of I(h), a hyperpolarization-activated inward cation current, to phase-transition in motor neurons during rhythmic firing. Motor neurons were recorded intracellularly during locomotion induced with a mixture of N-methyl-D- aspartate (NMDA) and serotonin, after pharmacological blockade of I(h). I(h) was then replaced by using dynamic clamp, a computer program that allows artificial conductances to be inserted into real neurons. I(h) was simulated with biophysical parameters determined in voltage clamp experiments. The data showed that electronic replacement of the native I(h) caused a depolarization of the average membrane potential, a phase- advance of the locomotor drive potential, and increased motor neuron spiking. Introducing an artificial leak conductance could mimic all of these effects. The observed effects on phase-advance and firing, therefore, seem to be secondary to the tonic depolarization; i.e., I(h) acts as a tonic leak conductance during locomotion. In the second half of this paper we discuss recent data showing that the neonatal rat spinal cord can produce a stable motor rhythm in the absence of spike activity in premotor interneuronal networks. These coordinated motor neuron oscillations are dependent on NMDA-evoked pacemaker properties, which are synchronized across gap junctions. We discuss the functional relevance for such coordinated oscillations in immature and mature spinal motor systems.'~Section of Neurophysiology, Department of Medical Physiology, University of Copenhagen, Copenhagen, Denmark. O.Kiehn@mfi.ku.dk11165800Brain Res Bull 2000535649-59.97062767Kilman, V. L. Marder, E.ZSUltrastructure of the stomatogastric ganglion neuropil of the crab, Cancer borealisAnimal Axons/physiology/ultrastructure Cell Count Crabs/*physiology Extracellular Space/metabolism Ganglia, Invertebrate/cytology/*ultrastructure Gap Junctions/physiology/ultrastructure GABA/metabolism Immunohistochemistry Lanthanum/metabolism Male Microscopy, Electron Neuroglia/ultrastructure Neurons/physiology/*ultrastructure Oligopeptides/metabolism Plastic Embedding Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Synapses/physiology/ultrastructure Tannic Acide The stomatogastric ganglion (STG) of the crab, Cancer borealis, contains the neural networks responsible for rhythmic pattern generation of the foregut. Neuron counts indicate that the STG of C. borealis has 25-26 neurons, 4-5 fewer than that found in lobsters. We describe the ultrastructural features of the ganglion by focusing on those that may be involved in storage, release, or range of action of peptide modulators, including a lacunar system and multiple types of intercellular junctions. In the neuropil, we identify five synaptic profile classes that contain the invertebrate presynaptic apparatus (dense bars, small clear vesicles), two of which also contain dense core (modulator-containing) vesicles. These latter two are comprised of multiple immunocytochemical classes that are not easily distinguished by structural criteria. In addition, we find neurohemal-like profiles that contain primarily dense core vesicles. Our finding that multiple profile types in the STG possess modulator-containing vesicles coincides with immunocytochemical results better than do previous ultrastructural studies that report only one such profile type. We show that a single modulatory input, stomatogastric nerve axon 1, makes only classical synapses and not neurohemal-like profiles, although some modulators are found in both these profile types. These data provide the groundwork for understanding the architecture of modulatory input- target interactions and suggest ways that the specificity of modulatory effects within a complex neuropil may be attained. J Comp Neurol 1996 3743 362-75ZShttp://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&dopt=r&uid=10340509dVOKilman, V. Fenelon, V. S. Richards, K. S. Thirumalai, V. Meyrand, P. Marder, E.tSequential developmental acquisition of cotransmitters in identified sensory neurons of the stomatogastric nervous system of the lobsters, Homarus americanus and Homarus gammarus Animal Digestive System/innervation Ganglia, Invertebrate/*chemistry Immunohistochemistry Lobsters/anatomy & histology/*chemistry Microscopy, Confocal Neurons, Afferent/*chemistry Neuropeptides/analysis Neurotransmitters/*analysis Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.We studied the developmental acquisition of three of the cotransmitters found in the gastropyloric receptor (GPR) neurons of the stomatogastric nervous systems of the lobsters Homarus americanus and Homarus gammarus. By using wholemount immunocytochemistry and confocal microscopy, we examined the distribution of serotonin-like, allatostatin-like, and FLRF(NH2)-like immunoreactivities within the stomatogastric nervous system of embryonic, larval, juvenile, and adult animals. The GPR neurons are peripheral sensory neurons that send proprioceptive information to the stomatogastric and commissural ganglia. In H. americanus, GPR neurons of the adult contain serotonin- like, allatostatin-like, and Phe-Leu-Arg-Phe-amide (FLRF(NH2))-like immunoreactivities. In the stomatogastric ganglion (STG) of the adult H. americanus and H. gammarus, all of the serotonin-like and allatostatin-like immunoreactivity colocalizes in neuropil processes that are derived exclusively from ramifications of the GPR neurons. In both species, FLRF(NH2)-like immunoreactivity was detected in the STG neuropil by 50% of embryonic development (E50). Allatostatin-like immunoreactivity was visible first in the STG at approximately E70-E80. In contrast, serotonin staining was not clearly visible until larval stage I (LI) in H. gammarus and until LII or LIII in H. americanus. These data indicate that there is a sequential acquisition of the cotransmitters of the GPR neurons.'b\Volen Center and Biology Department, Brandeis University, Waltham, Massachusetts 02454, USA.10340509 J Comp Neurol 1999 4083318-34.ztKim, M. Baro, D.J. Lanning, C.C. Doshi, M. Farnham, J. Moskowitz, H.S. Peck, J.H. Olivera, B.M. Harris-Warrick, R.M. 1997RLAlternative splicing in the pore-forming region of shaker potassium channels J Neurosci17 8213-8224e( '0& 76192974 King, D. G.yrkOrganization of crustacean neuropil. I. Patterns of synaptic connections in lobster stomatogastric ganglion^XAnimal Autonomic Fibers, Postganglionic/ultrastructure Autonomic Fibers, Preganglionic/ultrastructure Ganglia, Autonomic/cytology/*ultrastructure *Lobsters Mouth/innervation Neuroglia/ultrastructure Neurons/ultrastructure Stomach/innervation Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Synapses/*ultrastructure Synaptic VesiclesThe stomatogastric ganglion of the lobster consists of about thiry neurons, mainly large monopolar cells, which have been well characterized physiologically. This paper presents an anatomical description of this ganglion, emphasizing synaptic connections in the neuropil. The neuron cell bodies are located on the dorsal surface of the ganglion. They send processes into the underlying neuropil mass. The neuropil is differentiated into two regions: a core of coarse neuropil consists of large heavily ensheathed processes; a surrounding region of fine-textured synaptic neuropil consists of smaller unsheather processes. Synapses are found only in synaptic neuropil, not in the core of coarse neuropil. Synaptic contacts, about one million in the entire neuropil, are easily recognized by a set of criteria including presynaptic vesicles and pre- and postsynaptic membrane specializations. Most synaptic contacts invole at least three neural processes, usually one pre- and two postsynaptic elements. Synapses are clustered onto irregular swellings or varicosities on neural processes. These varicosities make both pre- and postsynaptic contacts. Three differenty types of presynaptic profile are recognized. Pyloric dilator, ventricular dilator and lateral posterior gastric neurons belong to type A with clear irregular synaptic vesicles. Lateral pyloric, pyloric, anterior median and dorsal gastric neurons belong to type B with larger clear round vesicles. Many unidentified fibres, presumably stomatogastric nerve afferents, blong to type C with both small clear irregular vesicles and also large dense-core vesicles. The synaptic vesicle types are tentatively correlated with neurotransmitter: type A with acetylcholine, type B with an unknown transmitter, possibly glutamate, and type C with dopamine. The distribution of synaptic contacts on the processes of identified neurons reconstructed from serial section is presented in