Effect of asynchronous GABA release on the oscillatory dynamics of inhibitory coupled neurons

Neuronal activities often exhibit rythmic patterns, with a frequency that changes from one band to another. These oscillations can be reproduced in network models of coupled inhibitors. However, the mechanism that controls the period of the oscillations is not fully understood. Recent studies have shown that various types of inhibitory interneurons may release transmitters synchronously or asynchronously. Could this diversity explain changes in the rythm of the oscillation? To answer this, we studied the effect of synchronous versus asynchronous inhibition, in a network of coupled inhibitory neurons. We observed that frequency and synchronization are reduced when release is asynchronous; the standard deviation of activity bursts increases linearly, while their period increases in a sublinear way. A mathematical analysis supports these observations. This suggests that the release mode of inhibition could play an important role in setting up the oscillatory frequency of inhibitory coupled neurons.