Electrical match between initial segment and somatodendritic compartment for action potential backpropagation in retinal ganglion cells

Sarah Goethals, Martijn C. Sierksma, Xavier Nicol, Annabelle Reaux-Le Goazigo, Romain Brette*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)
3 Downloads (Pure)

Abstract

The action potential of most vertebrate neurons initiates in the axon initial segment (AIS) and is then transmitted to the soma where it is regenerated by somatodendritic sodium channels. For successful transmission, the AIS must produce a strong axial current, so as to depolarize the soma to the threshold for somatic regeneration. Theoretically, this axial current depends on AIS geometry and Na+ conductance density. We measured the axial current of mouse retinal ganglion cells using whole cell recordings with post hoc AIS labeling. We found that this current is large, implying high Na+ conductance density, and carries a charge that covaries with capacitance so as to depolarize the soma by ∼30 mV. Additionally, we observed that the axial current attenuates strongly with depolarization, consistent with sodium channel inactivation, but temporally broadens so as to preserve the transmitted charge. Thus, the AIS appears to be organized so as to reliably backpropagate the axonal action potential.
Original languageEnglish
Pages (from-to)28-46
Number of pages19
JournalJournal of Neurophysiology
Volume126
Issue number1
Early online date26 May 2021
DOIs
Publication statusPublished - Jul 2021

Bibliographical note

Funding Information:
This work was supported by grants from Agence Nationale de la Recherche (ANR-14-CE13-0003, ANR-20-CE30-0025-01) to R.B., by a grant from Union Nationale des Aveugles et Déficients Visuels (17UU1166-00) to X.N., and by the Programme Investissements d’Avenir IHU FOReSIGHT (ANR-18-IAHU-01). R.B. is supported by Fondation Pour l’Audition (FPA RD-2017-2). S.G. is supported by the Ecole des Neurosciences de Paris.

Funding Information:
This work was supported by grants from Agence Nationale de la Recherche (ANR-14-CE13-0003, ANR-20-CE30-0025-01) to R.B., by a grant from Union Nationale des Aveugles et D?ficients Visuels (17UU1166-00) to X.N., and by the Programme Investissements d'Avenir IHU FOReSIGHT (ANR-18-IAHU-01). R.B. is supported by Fondation Pour l'Audition (FPA RD-2017-2). S.G. is supported by the Ecole des Neurosciences de Paris.

Publisher Copyright:
Copyright © 2021 the American Physiological Society.

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