Spiking statistics in noisy hippocampal interneurons

We have studied the e!ects of two types of noise in simple model neurons with Hodgkin} Huxley voltage-gated channels. We have considered Gaussian noise currents, and Poissondistributed excitatory and inhibitory postsynaptic potentials. We determined the distribution of interspike intervals, and calculated its average, q ISI , and the coe$cient of variation (CV). The neuronal dynamics is analyzed in the CV}q ISI diagram in terms of equi-noise strength D, and equi-drive I !11 curves. For the Gaussian case one can distinguish four regions of neuronal dynamics. An equivalent analysis is carried out in the Poisson case. In the latter case the behavior is more complicated. ( 1999 Elsevier Science B.V. All rights reserved.