Re: Genetic brain Pathways

Hi Lossy,
A short answer to your question is, yes, we are born with the genetic 
blueprint of how our brains should structure itself.  I assume you're 
looking for more.

Our bodies carry the genetic code for making every physical part of us.  
Developmentally, we follow a fairly rigid program, ie., at such and such a
time, neurons are born; neurons then extend processes--axons and dendrites;
processes migrate to make the right connections.  All this takes place at 
very defined time and space in our bodies.  This is why neurons don't 
regenerate.  The nerve cell in your spinal cord sends a process to your 
fingertip.  If the process is severed, no more sensations from your 
fingertip.  The neuron cannot regrow because 1) it has lost the potential 
to regenerate, 2) it cannot regrow through the already established muscles 
and other structures of the body.  

Clear examples of preprogrammed nervous system formation can be seen
in other organisms like, Drosophila (fruitfly) and the organism I worked on
for my thesis, Caenorhabditis elegans, a microscopic, non-parasitic roundworm.
Each cell, each connection, each neuronal pathway is the same from one 
worm to the next, EXCEPT when specific genes are mutated.  These genes are
responsible for the formation of the nervous system.  (For more technical 
information on what these genes are and how they work you could try 
accessing the ACEDB database.  This is the database of accumulated 
information on Caenorhabditis elegans.  They're on the web.  There should 
be accessible pictures of the nervous system.  There is also the Virtual
Fly Lab, you could do a Yahoo search to get the web access.  This site 
should also have pictures of Drosophila nervous system.)

So what you say?  How does the nervous system of other organisms concern 
us as human?  We didn't evolve in a vaccuum.  What nature likes, in terms 
of ways of organization, gets used again.  Many of the genes found in 
simpler organisms have similar homologues in higher organisms, eg. us.  The
brain/nervous system is just one of the systems being investigated in other
simpler animals and similarities are plenty.

Back to our brains, the brain is made up of millions of neurons, 
interconnected, wired within the brain, and connected to other organs of 
the body.  The BASIC structure of the brain eg., cerbellum, two hemispheres,
corpus collusum etc., is laid out in utero as we develop.  As we grow, new 
connection can be forged within the brain.  So a patient with a damaged
part of the brain can relearn tasks, rewire his brain.  This is what 
constitutes learning (and now I'm getting out of my milieu, you should ask
this as another question.)

I hope this answers your question.  I, myself, don't know the specifics 
about brain structural mutations in humans, but maybe others on the MSN 
can tell you.

Shirley Chan