Firing Frequency of Leaky Integrate-and-fire Neurons with Synaptic Current Dynamics

We consider a model of an integrate-and-fire neuron with synaptic current dynamics, in which the synaptic time constant t' is much smaller than the membrane time constant t. We calculate analytically the firing frequency of such a neuron for inputs described by a random Gaussian process. We find that the first order correction to the frequency due to t' is proportional to the square root of the ratio between these time constants, zt'/t. This implies that the correction is important even when the synaptic time constant is small compared with that of the potential. The frequency of a neuron with t'q 0 can be reduced to that of the basic IF neuron (corresponding to t'=0) using an ‘‘effective’’ threshold which has a linear dependence on zt'/t. Numerical simulations show a very good agreement with the analytical result, and permit an extrapolation of the ‘‘effective’’ threshold to higher orders in zt'/t. The obtained frequency agrees with simulation data for a wide range of parameters. 7 1998 Academic Press

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