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YEAR : 2018

Axon initial segment

AUTHORS : Debanne D, Garrido J.

JOURNAL : Encyclopedia of Life Sciences

The axon initial segment (AIS) is a specialised region of the axon where the action potential is initiated following integration of excitatory and inhibitory inputs. The AIS contains high density of sodium and potassium channels anchored on scaffold proteins, but it also includes receptors to neurotransmitters and neuromodulators. Besides its role in action potential initiation, the AIS constitutes a diffusion barrier that controls cytoplasmic traffic towards the axon. Activity-dependent plasticity has been recently shown to affect the length and position of the AIS whereas stimulation of ligand-gated receptors alters the ion channel content of the AIS. Thus, the AIS represents a critical element in neuronal excitability and its plasticity.