Time from input at a synapse to output

Richard Norman rsnorman at mediaone.net
Tue Apr 10 18:38:23 EST 2001

It is not really clear what is meant by "input at a synapse" and "output".
Specifically, where is the output measured?

5 ms is a rather long time for the synaptic delay, itself.  Synaptic delay
is often perhaps 0.5 to 1 ms, but it can be a bit longer in some cases.
But if the "output" under discussion might be some distance away.
At 50 m/s, an action potential could travel some 200 mm in 4 ms so
that a total response time 5 ms is possible.

It is surprisingly difficult to find actual numbers for synaptic delay in my
sources.  "Modern" texts talk about the delay and describe what causes
it (mostly the time it takes for Ca++ to enter the presynaptic terminal
and activate vesicle release), but don't give numbers.   I did find an
appropriate reference in

   Katz B, Miledi R.
  The effect of temperature on the synaptic delay at the
      neuromuscular junction.
  J Physiol. 1965;181(3):656-70

But since you say you can't get to the library, the reference alone is of
use.  I'll see if I can get a copy of that paper and send you more details.

"Jake Trexel" <jtrexel at ix.netcom.com> wrote in message
news:3AD347E2.6BBC9973 at ix.netcom.com...
> In the book "Speaking Minds", page 219, Dr. T. J. Sejnowski stated "To
> be precise: it takes about five milliseconds for a signal to go from
> input at a synapse to output."  The interview for this book was done
> back in 1988, even though it was published in 95.
> Due to my disability, I am not able to get to the Univ. lib to look up
> information that I need for my book, thus I am trying to find answers to
> questions such as the one I am going to post in this newsgroup.  So I
> would appreciate that any one that answers back, would you please
> reference your information.  I would appreciate it.
> ?  Is the statement that Dr. Sejnowski up to date ??
> thank you
> Professor F. J. Trexel
> jake
> jtrexel at ix.netcom.com

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