Impact of slow K+ currents on spike generation can be described by an adaptive threshold model

Abstract

A neuron that is stimulated by rectangular current injections initially responds with a high firing rate, followed by a decrease in the firing rate. This phenomenon is called spike-frequency adaptation and is usually mediated by slow K+ currents, such as the M-type K+ current (IM) or the Ca2+-activated K+ current (IAHP). It is not clear how the detailed biophysical mechanisms regulate spike generation in a cortical neuron. In this study, we investigated the impact of slow K+ currents on spike generation mechanism by reducing a detailed conductance-based neuron model. We showed that the detailed model can be reduced to a multi-timescale adaptive threshold model, and derived the formulae that describe the relationship between slow K+ current parameters and reduced model parameters. Our analysis of the reduced model suggests that slow K+ currents have a differential effect on the noise tolerance in neural coding.