On Tue, 16 Jul 2002 15:24:03 +0200, Laurent
<lorseau at ens.insa-rennes.fr> wrote:
>Hi !
>>I was wondering if a natural synapse could transmit a signal after and
>only after (and not instantly after) the source neuron has stopped being
>activated. Is this possible ?
>>Laurent.
Your question can be answered on many different levels of detail. How
much neurophysiology background do you have and how much detail do you
want? Are you really asking about synaptic delay?
Generally, the synapse releases transmitter as a result of being
depolarized. In many cases, that means that the axon has just fired
an action potential. The nerve activity causes the transmitter
release by starting a complex process involving calcium and vesicle
changes (here is where all the details occur).
It does take a brief time to crank up the machinery and here is where
most of the synaptic delay occurs. But if the action potential is
prolonged a bit, it is certainly possible for the transmitter to be
released before the action potential is finished, if that is what you
are asking. The delay can vary from a few hundred microseconds to a
msec or more depending on the cell and the synapse and the action
potential can have a similar variation in duration.
The most important thing is the the release machinery does not require
that the depolarization be removed before release can occur. So, yes,
it is possible.
