Inhibition potentiates the synchronizing action of electrical synapses

Benjamin Pfeuty
Frontiers in Computational Neuroscience. 2007-01-01; 1:
DOI: 10.3389/neuro.10.008.2007

1. Front Comput Neurosci. 2007 Nov 2;1:8. doi: 10.3389/neuro.10.008.2007.
eCollection 2007.

Inhibition potentiates the synchronizing action of electrical synapses.

Pfeuty B, Golomb D, Mato G, Hansel D.

In vivo and in vitro experimental studies have found that blocking electrical
interactions connecting GABAergic interneurons reduces oscillatory activity in
the gamma range in cortex. However, recent theoretical works have shown that the
ability of electrical synapses to promote or impede synchrony, when alone,
depends on their location on the dendritic tree of the neurons, the intrinsic
properties of the neurons and the connectivity of the network. The goal of the
present paper is to show that this versatility in the synchronizing ability of
electrical synapses is greatly reduced when the neurons also interact via
inhibition. To this end, we study a model network comprising two-compartment
conductance-based neurons interacting with both types of synapses. We
investigate the effect of electrical synapses on the dynamical state of the
network as a function of the strength of the inhibition. We find that for weak
inhibition, electrical synapses reinforce inhibition-generated synchrony only if
they promote synchrony when they are alone. In contrast, when inhibition is
sufficiently strong, electrical synapses improve synchrony even if when acting
alone they would stabilize asynchronous firing. We clarify the mechanism
underlying this cooperative interplay between electrical and inhibitory
synapses. We show that it is relevant in two physiologically observed regimes:
spike-to-spike synchrony, where neurons fire at almost every cycle of the
population oscillations, and stochastic synchrony, where neurons fire
irregularly and at a rate which is substantially lower than the frequency of the
global population rhythm.