IUBio

why study neurology?

mat mats_trash at hotmail.com
Tue Jan 15 15:20:24 EST 2002


"yan king yin" <y.k.y@(dont spam)lycos.com> wrote in message news:<PeV08.564$na5.75490 at news.xtra.co.nz>...
> Im thinking that perhaps the understanding of synaptic plasticity can
> *partly* answer the question of how is memory stored in the brain.
> Synapses are the functional units in the nervous system. If you find
> some transitors in an unknown machine, chances are that they store
> some bits of information, otherwise why are they being there?
> 

Of course :) synpatic plasticity miust be involved in memory, but the
function of memeory itself may not be reducible to individual synapse
but higher level networks

> Im wondering if the metabotropic receptors have secondary
> messengers that diffuse to nearby synapses and cross-talk with
> their pathways, thus modifying those synapses. This might give rise
> to some interesting learning rules. Thats just my guess and I have
> to study it more thoroughly.
> 
Well it depends what you mean...  For example, the activation of
Phospholipase A2 by diacylglycerol, and the subsequent liberation of
arachidonic acid which may cross synapses has been postualted as a
messenger to regulate LTP/LTD, particularly in the gluatmatergic
system.  Other second messengers (cAMP, IP3) due to the very nature of
their function have to be hydrophilic to be soluble in the cytosol and
diffuse to their targets.  Therefore, they would likely find it
difficult to escape through the cells' plasma membrane effectively
without some sort of channeling (Arachidonate is lipophilic and
doesn't suffer this problem).  You might conceive of a leaky membrane
I suppose, but then this offers little ability to regulate the
response as you would need to coordinate any useful function. 
Further, second messengers are usually broken down very rapidly after
receptor activation otherwise they would actually be of no use as
signalling molecules.  All in all I don't think it very likely for
cAMP or IP3 etc.. the current literature on arachidonic acid is very
confused

> Im also looking for some books on neural network modeling that
> is based closely on biological details, such as circuits and learning
> rules. Do you know of any?
> 
hmmm, what do you mean by biological details?  If you want to start
actually modelling neurones you're very brave :).  Just modelling a
single ion channel is immensely complex.  Not only that, there's the
cell's morphology, up to 100,000 synapses to model. How will the
synapses integrate? Are you going to model the protein dynamics too? 
As you can see the amount of stuff is just too much.  The best you can
do is start from the premise of extremely simple 'neurones' i.e.
binary operators, and work up,  gradually building in things like
probabilistic operators (the paramaters of which you can estimate from
real-neuron recordings) etc..  MIT press (http://www-mitpress.mit.edu 
especially books by Michael Arbib) Springer (http://www.springer.de)
and Wiley (http://www.wiley.com) all publish some good books on this
kind of thing

I would also look up G. Buzsaki (Rutgers University), A. Abbott, P.A.
Robinson (Sydney) and Walter Freeman at California somewhere for
research groups in this kind of area




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