title: Node of Ranvier length as a potential regulator of myelinated axon conduction speed.
abstract: Myelination speeds conduction of the nerve impulse, enhancing cognitive power. Changes of white matter structure contribute to learning, and are often assumed to reflect an altered number of myelin wraps. We now show that, in rat optic nerve and cerebral cortical axons, the node of Ranvier length varies over a 4.4-fold and 8.7-fold range respectively and that variation of the node length is much less along axons than between axons. Modelling predicts that these node length differences will alter conduction speed by ~20%, similar to the changes produced by altering the number of myelin wraps or the internode length. For a given change of conduction speed, the membrane area change needed at the node is >270-fold less than that needed in the myelin sheath. Thus, axon-specific adjustment of node of Ranvier length is potentially an energy-efficient and rapid mechanism for tuning the arrival time of information in the CNS.
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
authors.forename: I Lorena
authors.initials: IL
authors.lastname: Arancibia-Cárcamo
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
authors.forename: Marc C
authors.identifier: 0000-0003-0472-2652
authors.initials: MC
authors.lastname: Ford
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
authors.forename: Lee
authors.initials: L
authors.lastname: Cossell
authors.affiliation: The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Morioka, Japan.
authors.forename: Kinji
authors.initials: K
authors.lastname: Ishida
authors.affiliation: The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Morioka, Japan.|Department of Physiology, School of Dentistry, Iwate Medical University, Morioka, Japan.
authors.forename: Koujiro
authors.initials: K
authors.lastname: Tohyama
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
authors.forename: David
authors.identifier: 0000-0003-3618-0843
authors.initials: D
authors.lastname: Attwell
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D056808:Biostatistics; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology; D008954:Models, Biological; D009431:Neural Conduction; D009900:Optic Nerve / Q000166:cytology / Q000502:physiology; D011901:Ranvier's Nodes / Q000502:physiology*; D051381:Rats
keywords: axon; conduction speed; myelin; neuroscience; node of Ranvier; rat