GABA Reversal Pontetials Control Synchronization of Neuronal Oscillators

Ho Young Jeong (2) and Boris Gutkin (1)
(1) Group for Neural Theory, DEC, ENS-Paris and Department of Neuroscience, Institut Pasteur, Paris
(2)Center for Neural Science, New York University, New York, NY USA

GABA$_A$ergic synapse reversal potential is controlled by the concentration of chloride. This concentration can change significantly during development and as a function of neuronal activity. Thus GABA inhibition can be hyperpolarizing, shunting or partially depolarizing. Previous results pint-pointed the conditions under which hyperpolarizing inhibition (or depolarizing excitation) can lead to synchrony of neural oscillators. Here we examine the role of the GABAergic reversal potential in generation of synchronous oscillations in circuits of neural oscillators. Using weakly coupled oscillator analysis we show when shunting and partially depolarizing inhibition can produce synchrony, asynchrony and co-existence of the two. In particular, we show that this depends critically on such factors as the firing rate, the speed of the synapse, spike frequency adaptation and most importantly on the dynamics of spike generation (type I vs. type II). We back up our analysis with directly simulations of small circuits of conductance based neurons as well as large-scale networks of neural oscillators. The simulation results are compatible with the analysis: e.g. when bistability is predicted analytically the large scale-network shows clustered states.