Frequency Regulation of a Slow Rhythm by a Fast
Periodic Input
Farzan Nadim, Yair Manor, Michael P. Nusbaum and Eve Marder
Abstract
Many nervous systems contain 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 gastric mill
period produced by the pyloric to gastric mill interaction 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 modulate the slow rhythm
either directly and/or indirectly by modulating the faster rhythm.
