Repolarization Time of Neuron

Allen Smith allens at yang.earlham.edu
Sun Apr 12 22:22:21 EST 1992

Message-ID: <9204062228.AA17922 at aragorn.stanford.edu>
From: mbieda at ARAGORN.STANFORD.EDU (Mark Bieda)

>1) You are really asking about the "refractory period", which is quite distinct
>from the "repolarization time". The absolute refractory period, which is the
>time after an action potential that a neuron is absolutely unable to fire
>another action potential, has a textbook value of 1 msec. Now, this masks a
>great range`of firing frequencies - 1 kHz is usually considered an absolute
>upper bound, with 800 Hz or so the highest I've seen in print. (Any
>counterexamples out there?)
>2) Your definition does not accord with the neuronal reality of repolarization.
>In short, a neuron need not repolarize to fire another action potential (e.g.
>thousands of examples of plateau potentials with burst firing, in both
>vertebrate and invertebrate systems).
>3) Assuming that you are making neocortical mammalian models, you might
>want to look at work from the laboratory of John Connors, among others. There
>was a relatively recent TINS review on this subject.
>4) If only we could model a single neuron realistically....

Message-ID: <1992Apr07.122443.114219 at link-1.ts.bcc.ac.uk>
From: smgxt01 at ucl.ac.uk (Dr Thomas Salt)

>>What is the repolarization time of a neuron in the brain?
>>Repolarization time is defined here as the time
>>AFTER firing of the neuron and BEFORE the neuron is
>>ready to fire AGAIN.

>Strictly speaking, repolarisation time is the time it takes for the
>membrane potential to return to rest from the peak of the depolarising
>phase of the action potential.  This is generally less than 1ms in
>normal neurones.  Following repolarisation, there is a period called
>the refractory period during which it is impossible/difficult to evoke
>subsequent action potentials.  The length of this period is very
>variable from neuron type to neuron type and can be hundred of ms
>long, or only a few tens...  'it depends'.

        There seems to be a contradiction in the definitions of refractory
period and repolarization time. What's the name for how long it takes
before a neuron can send a signal again? On what does it primarily depend
(myelinated/non-mylelinated, or what)?


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