POTASSIUM CURRENT MODULATE SYNCHRONIZATION IN NETWORKS OF NEURONS CONNECTED WITH ELECTRICAL SYNAPSES

B. PFEUTY; D. GOLOMB; G. MATO; D. HANSEL

Orlando, FL, USA

Conferencia; Society for Neuroscience Meeting; 2002

Society for Neuroscience

The existence of electrical synapses (ES) has been recently assessed in many regions of the mammalian brain. It has been also found that the spikes fired by interneurons interconnected with ES may get tightly synchronized. Here we investigate theoretically the conditions of emergence of synchronous activity in large networks of neurons coupled with ES. We consider two models. In the first one, which is analytically tractable, the neurons are fully connected and they are modeled with the "quadratic integrate-and-fire" dynamics which is a good approximation for the subthreshold behavior of a large class of neurons. The second model consists of randomly connected conductance-based neurons in which the shape of the spike and of the after-hyperpolarization (AHP) can be controlled by a potassium current. We show analytically and numerically that the stability of the asynchronous state (AS) depends on the shape of the action potentials fired by the neurons and of the after-hyperpolarization (AHP) which follows it. This work clarifies the respective effects of the AHP, the spike shape and the synaptic conductance in the destabilization of the AS. It predicts that blockade or activation of fast potassium current can modify the level of synchrony mediated by electrical synapses. In particular, we suggest that in a large class of neurons AHP currents promote synchrony mediated by ES.