Q: dendrites/gates

Matthew Kirkcaldie m.kirkcaldie-remove at unsw.edu.au
Sun Mar 20 21:27:21 EST 2005


In article <ir9s31tlhhpmmtpplufie8hdiov0qnnnrd at 4ax.com>,
 r norman <rsn_ at _comcast.net> wrote:

> Still, the real "transmission" of the action potential, as you say, is
> the successive replication of a completely new action potential at
> each node.  The longitudinal flow of current is simply the decremental
> spread of activity that is the mechanism underlying the triggering.
> 
> If find that it usually takes two or three rounds of courses for
> students to really start to get it.  It starts in intro biology and
> continues in animal physiology.  By the third time in a specialized
> neuro course, it finally starts to really sink in and gel.

I find the Mexican wave analogy does it every time - the action 
potential corresponds to each person standing up and sitting back down, 
nothing physically moves overall.  The length constant is how many seats 
away you're looking to get your cue for when to stand, and the time 
constant is what you use for the cue - the person starting to move, or 
when they have fully stood, etc.  Myelin is empty seats between crowd 
members - forces them to take their cues from further away.  I've had a 
lecture audience do it for me!

I find the analogy is surprisingly precise, to the extent that I 
sometimes use it to remember this stuff myself!  Pity there's not really 
anything you can liken to a current though.

      Cheers,

         MK.



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