Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.

This study explores in detail the functional consequences of subtle retraction and detachment of myelin around the nodes of Ranvier following mild-to-moderate crush or stretch mediated injury. An equivalent electrical circuit model for a series of equally spaced nodes of Ranvier was created incorpor...

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Autores principales:	Charles F Babbs, Riyi Shi
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/10f181ded42a4d8cbf8fd5599238f23a
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spelling	oai:doaj.org-article:10f181ded42a4d8cbf8fd5599238f23a2021-11-18T07:38:48ZSubtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.1932-620310.1371/journal.pone.0067767https://doaj.org/article/10f181ded42a4d8cbf8fd5599238f23a2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23844090/?tool=EBIhttps://doaj.org/toc/1932-6203This study explores in detail the functional consequences of subtle retraction and detachment of myelin around the nodes of Ranvier following mild-to-moderate crush or stretch mediated injury. An equivalent electrical circuit model for a series of equally spaced nodes of Ranvier was created incorporating extracellular and axonal resistances, paranodal resistances, nodal capacitances, time varying sodium and potassium currents, and realistic resting and threshold membrane potentials in a myelinated axon segment of 21 successive nodes. Differential equations describing membrane potentials at each nodal region were solved numerically. Subtle injury was simulated by increasing the width of exposed nodal membrane in nodes 8 through 20 of the model. Such injury diminishes action potential amplitude and slows conduction velocity from 19.1 m/sec in the normal region to 7.8 m/sec in the crushed region. Detachment of paranodal myelin, exposing juxtaparanodal potassium channels, decreases conduction velocity further to 6.6 m/sec, an effect that is partially reversible with potassium ion channel blockade. Conduction velocity decreases as node width increases or as paranodal resistance falls. The calculated changes in conduction velocity with subtle paranodal injury agree with experimental observations. Nodes of Ranvier are highly effective but somewhat fragile devices for increasing nerve conduction velocity and decreasing reaction time in vertebrate animals. Their fundamental design limitation is that even small mechanical retractions of myelin from very narrow nodes or slight loosening of paranodal myelin, which are difficult to notice at the light microscopic level of observation, can cause large changes in myelinated nerve conduction velocity.Charles F BabbsRiyi ShiPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 7, p e67767 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Charles F Babbs Riyi Shi Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
description	This study explores in detail the functional consequences of subtle retraction and detachment of myelin around the nodes of Ranvier following mild-to-moderate crush or stretch mediated injury. An equivalent electrical circuit model for a series of equally spaced nodes of Ranvier was created incorporating extracellular and axonal resistances, paranodal resistances, nodal capacitances, time varying sodium and potassium currents, and realistic resting and threshold membrane potentials in a myelinated axon segment of 21 successive nodes. Differential equations describing membrane potentials at each nodal region were solved numerically. Subtle injury was simulated by increasing the width of exposed nodal membrane in nodes 8 through 20 of the model. Such injury diminishes action potential amplitude and slows conduction velocity from 19.1 m/sec in the normal region to 7.8 m/sec in the crushed region. Detachment of paranodal myelin, exposing juxtaparanodal potassium channels, decreases conduction velocity further to 6.6 m/sec, an effect that is partially reversible with potassium ion channel blockade. Conduction velocity decreases as node width increases or as paranodal resistance falls. The calculated changes in conduction velocity with subtle paranodal injury agree with experimental observations. Nodes of Ranvier are highly effective but somewhat fragile devices for increasing nerve conduction velocity and decreasing reaction time in vertebrate animals. Their fundamental design limitation is that even small mechanical retractions of myelin from very narrow nodes or slight loosening of paranodal myelin, which are difficult to notice at the light microscopic level of observation, can cause large changes in myelinated nerve conduction velocity.
format	article
author	Charles F Babbs Riyi Shi
author_facet	Charles F Babbs Riyi Shi
author_sort	Charles F Babbs
title	Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
title_short	Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
title_full	Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
title_fullStr	Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
title_full_unstemmed	Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
title_sort	subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/10f181ded42a4d8cbf8fd5599238f23a
work_keys_str_mv	AT charlesfbabbs subtleparanodalinjuryslowsimpulseconductioninamathematicalmodelofmyelinatedaxons AT riyishi subtleparanodalinjuryslowsimpulseconductioninamathematicalmodelofmyelinatedaxons
_version_	1718423142644318208

Subtle paranodal injury slows impulse conduction in a mathematical model of myelinated axons.

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