[Neuroscience] Re: membrane voltage equations which one

r norman via neur-sci%40net.bio.net (by r_s_norman from comcast.net)
Mon Sep 6 22:32:59 EST 2010


On Mon, 6 Sep 2010 18:08:11 -0700 (PDT), Bill
<connelly.bill from gmail.com> wrote:

>On Sep 7, 10:52 am, r norman <r_s_nor... from comcast.net> wrote:
>, when they computed the action potential based on their
>> voltage clamp data and used the simple ohmic relationship, it was not
>> at all for lack of knowledge.  The finest details of the shape of the
>> action potential don't really matter:  
>
>Oh, I in no way meant any disrespect to the original H-H model, not
>its use in modern computational neuroscience. I was just simply
>wondering allowed, what it would look like if you computer a 'H-H
>action potential' (read:ohmic) and one with the GHK equation used
>instead. Whether there would be any noticeable difference, and how and
>where that difference would manifest itself.

The reason for my answer was to indicate my impression (I don't know
for certain) that if it mattered, then it would have been done the
hard way.   My guess, having done H-H simulations and having taught
the biophysics behind all of that, is that any difference would be
quite trivial.  My impression is that the rising edge of the action
potential is so swift that any change would be imperceptible.  The
falling edge and any hesitation about the timing of the repolarization
might vary a bit but again my impression (without doing the actual
calculations) is that the difference would probably be comparable to
or even less than the variation in the shape of the action potenial
from time to time due to normal variations in ion concentrations and
numbers of ion channels in various states.  It certainly would be far
less than the variation in action potential shape from cell type to
cell type.



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