ANALYSIS OF NEURON MODELS WITH DYNAMICALLY REGULATED CONDUCTANCES

We analyze neuron models in which the maximal conductances of membrane currents are slowly varying dynamic variables regulated by the intrac ellular calcium concentration. These models allow us to study possible activity-dependent effects arising from processes that maintain and m odify membrane channels in real neurons. Regulated model neurons maint ain a constant average level of activity over a wide range of conditio ns by appropriately adjusting their conductances. The intracellular ca lcium concentration acts as a feedback element linking maximal conduct ances to electrical activity. The resulting plasticity of intrinsic ch aracteristics has important implications for network behavior. We firs t study a simple two-conductance model, then introduce techniques that allow us to analyze dynamic regulation with an arbitrary number of co nductances, and finally illustrate this method by studying a seven-con ductance model. We conclude with an analysis of spontaneous differenti ation of identical model neurons in a two-cell network.