HOW INTRINSIC PROPERTIES AFFEC TPHASE LOCKING OF NEURONS COUPLED VIA ELECTRICAL AND GABAERGIC SYNAPSES.

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

New Orleans, USA

Conferencia; Society for Neuroscience Meeting; 2003

Society for Neuroscience

Electrical synapses are ubiquitous in the mammalian central nervous system. In neocortex, electrical synapses have been shown to connect Low Threshold Spiking (LTS) as well as Fast Spiking (FS) GABAergic interneurons. Here we investigate theoretically how intrinsic cell and synaptic properties affect the locking of a pair of tonically firing two compartment neurons coupled via electrical and GABAergic synapses. In a first model, the dynamics of the soma is described by the quadratic integrate-and-fire model. Under the assumption of weak coupling we compute analytically the distribution of phase shifts of the two neurons as a function of the synaptic types and parameters, synaptic locations and of the parameters of the somatic dynamics.In particular, we find that this distribution depends crucially on the refractoriness of the neurons and on the location of the synapses. Electrical synapses promote in-phase (resp. anti-phase) locking for neurons with strong (resp. weak) refractoriness following spike firing. Dendritic electrical synapses tend to promote anti-phase locking compared to somatic synapses. In contrast with electrical synapses, GABAergic interactions favor in-phase locking except at low firing rate and for strong refractoriness.Using numerical simulations we verify that these conclusions hold for a broad range of coupling. We have also performed numerical simulations to confirm that these results remain valid for conductance-based models in which the refractoriness depends on the ionic currents. We use this framework to perform a feasibility study for experimental tests of our predictions using the dynamic clamp technique.