Synaptic Depression Creates a Switch That
Controls the Frequency of an Oscillatory Circuit
Farzan Nadim, Yair Manor, Nancy Kopell and Eve Marder
Description (not the Abstract)
Synaptic depression is a property of many synapses, but the functional contributions of
synaptic depression to circuit dynamics are only now beginning to be understood. When
depressing synapses are found in rhythmically active networks, the relationship between
the kinetics of
depression and its recovery and the period of the network may result in a steady-state
condition in which the synapse is significantly depressed. We demonstrate that synaptic
depression in a recurrent inhibitory network that includes an intrinsic oscillator can
give rise to a switch between two distinct modes of network operation. When the depressing
synapse is weak, the oscillation period is determined by the oscillator component.
Increasing the strength of the depressing synapse beyond a threshold value activates a
positive feedback mechanism. In this regime the oscillation period is determined by the
depressing synapse.
