The Effect of synchronized inputs at the single neuron level
It is commonly assumed that temporal synchronization of excitatory synaptic inputs onto a single neuron increases its firing rate. We investigate here the role of synaptic synchronization for the leaky integrate-and-fire neuron as well as for a biophysically and anatomically detailed compartmental model of a cortical pyramidal cell. We find that if the number of excitatory inputs, N, is on the same order as the number of fully synchronized inputs necessary to trigger a single action potential, N_t, synchronization always increases the firing rate (for both constant and Poisson-distributed input). However, for large values of N compared to N_t, ''overcrowding'' occurs and temporal synchronization is detrimental to firing frequency. This behavior is caused by the conflicting influence of the low-pass nature of the passive dendritic membrane on the one hand and the refractory period on the other. If both temporal synchronization as well as the fraction of synchronized inputs (Murthy and Fetz 1993) is varied, synchronization is only advantageous if either N or the average input frequency, ƒ(in), are small enough.
© 1994 MIT Press. Received March 4, 1993; accepted July 29, 1993. Posted Online April 4, 2008. We wish to thank Ernst Niebur and William Softky for helpful comments. The research was supported by the Air Force Office of Scientific Research, the Office of Naval Research and the National Institute of Mental Health. Marius Usher was supported by a Myron A. Bantrell Research Fellowship.
Published - BERnc94.pdf