Conditions under which Na+ channels can boost conduction of small graded potentials

G. C. Taylor, J. A. Coles, J. C. Eilbeck

Research output: Contribution to journalArticle

Abstract

It has recently become apparent that in the dendrites or short axons of some neurons, voltage-dependent sodium channels are used not to generate action potentials but to modulate graded potentials; graded potentials carry far more information than do action potentials. A model axon (or dendrite) is described in which sodium channels with kinetics described by equations of the Hodgkin-Huxley type boost conduction of small voltage signals. For a sodium channel density beyond a certain minimum there exists an optimal potential, depolarized with respect to the resting potential, at which there is no steady-state decrement along the axon. For an axon not longer than about 0.7 length constants, small, steady-state deviations from this optimal potential imposed at one end of the axon appear amplified in a graded and stable way at the other end. A small pulse of potential is propagated with amplification and more rapidly than in an axon with a passive membrane. Compared to passive propagation, there will be an improvement in signal-to-noise ratio at the synapse; the axon also acts as a selective frequency filter. The same axon is capable of conducting an action potential.

Original languageEnglish
Pages (from-to)379-386
Number of pages8
JournalJournal of Theoretical Biology
Volume172
Issue number4
DOIs
Publication statusPublished - 1995

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axons
acceleration (physics)
conduction
dendrites
synapses
electric potential
neurons
signal to noise ratios
membranes
deviation
filters
propagation
kinetics

Cite this

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title = "Conditions under which Na+ channels can boost conduction of small graded potentials",
abstract = "It has recently become apparent that in the dendrites or short axons of some neurons, voltage-dependent sodium channels are used not to generate action potentials but to modulate graded potentials; graded potentials carry far more information than do action potentials. A model axon (or dendrite) is described in which sodium channels with kinetics described by equations of the Hodgkin-Huxley type boost conduction of small voltage signals. For a sodium channel density beyond a certain minimum there exists an optimal potential, depolarized with respect to the resting potential, at which there is no steady-state decrement along the axon. For an axon not longer than about 0.7 length constants, small, steady-state deviations from this optimal potential imposed at one end of the axon appear amplified in a graded and stable way at the other end. A small pulse of potential is propagated with amplification and more rapidly than in an axon with a passive membrane. Compared to passive propagation, there will be an improvement in signal-to-noise ratio at the synapse; the axon also acts as a selective frequency filter. The same axon is capable of conducting an action potential.",
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Conditions under which Na+ channels can boost conduction of small graded potentials. / Taylor, G. C.; Coles, J. A.; Eilbeck, J. C.

In: Journal of Theoretical Biology, Vol. 172, No. 4, 1995, p. 379-386.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Conditions under which Na+ channels can boost conduction of small graded potentials

AU - Taylor, G. C.

AU - Coles, J. A.

AU - Eilbeck, J. C.

PY - 1995

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AB - It has recently become apparent that in the dendrites or short axons of some neurons, voltage-dependent sodium channels are used not to generate action potentials but to modulate graded potentials; graded potentials carry far more information than do action potentials. A model axon (or dendrite) is described in which sodium channels with kinetics described by equations of the Hodgkin-Huxley type boost conduction of small voltage signals. For a sodium channel density beyond a certain minimum there exists an optimal potential, depolarized with respect to the resting potential, at which there is no steady-state decrement along the axon. For an axon not longer than about 0.7 length constants, small, steady-state deviations from this optimal potential imposed at one end of the axon appear amplified in a graded and stable way at the other end. A small pulse of potential is propagated with amplification and more rapidly than in an axon with a passive membrane. Compared to passive propagation, there will be an improvement in signal-to-noise ratio at the synapse; the axon also acts as a selective frequency filter. The same axon is capable of conducting an action potential.

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