document: Integrate-and-fire neurons driven by correlated stochastic input Neurons are sensitive to correlations among synaptic inputs . However , analytical models that explicitly include correlations are hard to solve analytically , so their influence on a neuron 's response has been difficult to ascertain . To gain some intuition on this problem , we studied the firing times of two simple integrate-and-fire model neurons driven by a correlated binary variable that represents the total input current . Analytic expressions were obtained for the average firing rate and coefficient of variation -LRB- a measure of spike-train variability -RRB- as functions of the mean , variance , and correlation time of the stochastic input . The results of computer simulations were in excellent agreement with these expressions . In these models , an increase in correlation time in general produces an increase in both the average firing rate and the variability of the output spike trains . However , the magnitude of the changes depends differentially on the relative values of the input mean and variance : the increase in firing rate is higher when the variance is large relative to the mean , whereas the increase in variability is higher when the variance is relatively small . In addition , the firing rate always tends to a finite limit value as the correlation time increases toward infinity , whereas the coefficient of variation typically diverges . These results suggest that temporal correlations may play a major role in determining the variability as well as the intensity of neuronal spike trains
doc_bio_tags: O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O B I I O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O B I O O O O O O O O O O O O O O O O O O
extractive_keyphrases: correlated stochastic input firing times correlated binary variable coefficient of variation output spike trains temporal correlations
abstractive_keyphrases: integrate-and-fire neurons synaptic input correlations spike-train variability computer simulation