Laurent wrote/ecrivait:
> Ok ! thanks, Richard and Brian !
>> So it can take quite a while for the transmitters to go accross the synaptic
> cleft.
> It is that delay I was 'thinking' about.
Salut,
If I remember well, this step, called integration is not a post signal, as it
cannot increase after stimulation of the presynaptic neuron, and this
integration is unitary, integrated with other synapses signals to provoque
or not a post synaptic signal.
So I am not sure IMHO, you can consider it a post-signal, rather a remaining
signal
> For a single synapse, could this delay vary a lot with time ?
depending on previous neuroTr emission I presume
> Or does it just
> attempt to match the right delay to work properly for that synapse's function ?
> Is there a relation between that delay and the time period during which the
> transmitters are caught by the target neuron ? That might depend on the amount
> of transmitters, no ?
> And does the type of transmitters affect the time it takes to go accross the
> synaptic cleft ?
Yes, you have to refer to the binding kinetics in enzymology, which have similar
laws to receptor/activator binding properties.
The laws are referred to as Lineweaver-Burke curves and derivated (Hill or
Scatchard representation). They use a kinetic model.
However the case of a synapse is a more complex case of this model.
Hope this helps,
Fred
> Thalamus wrote:
>>> Bon soir Laurent,
>> Sorry for putting my .02 ? in here.
>>>> "Laurent" <lorseau at ens.insa-rennes.fr> skrev i melding
>> news:3D34371D.EDB8F929 at ens.insa-rennes.fr...>> > Thanks a lot.
>> > Anyway, I may have not explain correctly what I wanted, or I don't
>> > understand well enough what you say.
>> >
>> > I have some basic notions about neurons and chemistry, but I haven't tried
>> > to know the whole phenomena of the synapse.
>> >
>> > Here is what I wanted know if it was possible :
>> >
>> > Neuron A is activated since a few msec (or less or even more).
>> > Neuron A suddenly desactivates.
>> > Wait some msec.... (delay, no signal in A's axon, nor through Synapse S)
>> > Synapse S from neuron A (still desactivated) to neuron B then transmits a
>> > signal.
>>>> Yes, and Richard said so,no ?
>> Neuron A activates a _potential_; ae electrical signal that courses through
>> the axon (which is the output from the neuron) to the end-terminal (where
>> the neurotransmitters are stored in vesicles [containers]).
>> Then this signal activates intake of Ca+ (Calsium), which releases vesicles
>> (small containers) with neurotransmitters inside them - those vesicles
>> 'integrates' then with the cellular membrane and the neurotransmitters are
>> released outside of the cell.
>> Then it takes some time for these neurotransmitter to diffuse across the
>> synaptic cleft (the distance between the terminal of neuron A, and the
>> cellular wall of neuron B) were it activate _reseptors_ on neuron B.
>> The time it takes from when the signal activates the intake of Ca+ to the
>> release of the vesicles is very short.
>> And Richard thinks of the time for the neurotransmitter to _diffuse_ from
>> neuron A to neuron B; while you are thinking of the time-delay from when the
>> signal _activates_ the Ca+ intake.
>> Chemically it is the neurotransmitter which is interesting if you are
>> searching for a delay, so he gave you the right answer.
>> Hope I have helped clearifying things, Laurent.
>>>> Brian
>
--
n i k o
la faq de pages-perso: http://colino.net/fciwpp
