Diversity of firing frequency control by A-currents in vertebrate neurons:a modeling study

EXPERIMENTAL and modeling studies have accumulated strong evidence suggesti ng that A-currents control firing rates in invertebrate neurons. However, t he direct demonstration of a similar role remains to be established in vert ebrate neurons. We tested this possibility in a simulated neuron embedded w ith a generic model of vertebrate A-currents. Under simulated current-damp protocols, the generic A-current produced a modest frequency reduction (15 Hz) that was constant within all firing frequencies. Modifications in stead y-state properties of the A-current model within known physiological ranges annihilated or dramatically increased firing frequency reduction. These re sults suggest that the influence of A-currents on firing frequency should d iffer strongly among vertebrate neurons, and that modulations influencing A -currents provide a powerful control over the excitability of vertebrate ne urons. (C) 1999 Lippincott Williams & Wilkins.