How spike generation mechanisms determine the neuronal response to fluctuating inputs.

Published

Journal Article

This study examines the ability of neurons to track temporally varying inputs, namely by investigating how the instantaneous firing rate of a neuron is modulated by a noisy input with a small sinusoidal component with frequency (f). Using numerical simulations of conductance-based neurons and analytical calculations of one-variable nonlinear integrate-and-fire neurons, we characterized the dependence of this modulation on f. For sufficiently high noise, the neuron acts as a low-pass filter. The modulation amplitude is approximately constant for frequencies up to a cutoff frequency, fc, after which it decays. The cutoff frequency increases almost linearly with the firing rate. For higher frequencies, the modulation amplitude decays as C/falpha, where the power alpha depends on the spike initiation mechanism. For conductance-based models, alpha = 1, and the prefactor C depends solely on the average firing rate and a spike "slope factor," which determines the sharpness of the spike initiation. These results are attributable to the fact that near threshold, the sodium activation variable can be approximated by an exponential function. Using this feature, we propose a simplified one-variable model, the "exponential integrate-and-fire neuron," as an approximation of a conductance-based model. We show that this model reproduces the dynamics of a simple conductance-based model extremely well. Our study shows how an intrinsic neuronal property (the characteristics of fast sodium channels) determines the speed with which neurons can track changes in input.

Full Text

Duke Authors

Cited Authors

  • Fourcaud-Trocmé, N; Hansel, D; van Vreeswijk, C; Brunel, N

Published Date

  • December 17, 2003

Published In

Volume / Issue

  • 23 / 37

Start / End Page

  • 11628 - 11640

PubMed ID

  • 14684865

Pubmed Central ID

  • 14684865

Electronic International Standard Serial Number (EISSN)

  • 1529-2401

Language

  • eng

Conference Location

  • United States