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

Experimental and modeling studies have accumulated strong evidence suggesting that A-currents control firing rates in invertebrate neurons. However, the direct demonstration of a similar role remains to be established in vertebrate neurons. We tested this possibility in a simulated neuron embedded with a generic model of vertebrate A-currents. Under simulated current-clamp protocols, the generic A-current produced a modest frequency reduction (15 Hz) that was constant within all firing frequencies. Modifications in steady-state properties of the A-current model within known physiological ranges annihilated or dramatically increased firing frequency reduction. These results suggest that the influence of A-currents on firing frequency should differ strongly among vertebrate neurons, and that modulations influencing A-currents provide a powerful control over the excitability of vertebrate neurons.