Theoretical relation between axon initial segment geometry and excitability - Sorbonne Université
Journal Articles eLife Year : 2020

Theoretical relation between axon initial segment geometry and excitability

Romain Brette

Abstract

In most vertebrate neurons, action potentials are triggered at the distal end of the axon initial segment (AIS). Both position and length of the AIS vary across and within neuron types, with activity, development and pathology. What is the impact of AIS geometry on excitability? Direct empirical assessment has proven difficult because of the many potential confounding factors. Here, we carried a principled theoretical analysis to answer this question. We provide a simple formula relating AIS geometry and sodium conductance density to the somatic voltage threshold. A distal shift of the AIS normally produces a (modest) increase in excitability, but we explain how this pattern can reverse if a hyperpolarizing current is present at the AIS, due to resistive coupling with the soma. This work provides a theoretical tool to assess the significance of structural AIS plasticity for electrical function.

Domains

Neuroscience
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Dates and versions

hal-02586117 , version 1 (15-05-2020)

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Sarah Goethals, Romain Brette. Theoretical relation between axon initial segment geometry and excitability. eLife, 2020, 9, ⟨10.7554/eLife.53432⟩. ⟨hal-02586117⟩
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