Somatic modulation of ectopic action potential initiation in distal axons

Abstract : Classically, action potentials are initiated at the axon initial segment (AIS) when the summed depolarizing events arising from the dendrites exceed a threshold value. Then, action potentials propagate along the axon before reaching presynaptic terminals where they cause local calcium influx and transmitter release. According to this scheme, the AIS is a major player since all propagated excitation is precisely initiated at this hot spot endowed with a high concentration of sodium channels.