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I'd like gain more knowledge of different parts of the brain!

dag.stenberg at helsinki.nospam.fi dag.stenberg at helsinki.nospam.fi
Fri Oct 2 09:04:15 EST 1998

R. Storm <rstorm at best.ms.philips.com> wrote:
> I'm trying to develop computer models of biological Neural Networks.
> But, because I don't know much about neuroscience (the more about computer
> science) I have some questions about the different parts of a brain 
(especially mammalian).
> I would like to know more information on networks and neurons in different
> parts of the brain like:
... <shopping list>

As several others have pointed out here, the subject is too vast for any
reasonable reply, and you should do some reading. Excellent textbooks
  Bear etc. Neuroscience. Exploring the brain (Williams & Wilkins)
  Purves etc. Neuroscience. (Sinauer)
  Kandel etc. Essentials ofNeural Science and Behavior (Prentice Hall)
  - the big Kandel: Principles of Neural Science is good, but perhaps too
    big a chunk for a non-neuroscientist
  Shepherd: Neurobiology (Oxford University Press) is good, but with a
different emphasis from all the others: very comparative, i.e. tells us
about nonmallals also.

About the areas you ask about
> Cerebrum,
well studied, has some general principles in its design. Please note the
very different connections and actions of elementary and complex cells
> Septum,
its essential mechanisms can easily be understood
> Amygdala,
anatomy has been studied, but the detailed study of function is at an
early stage. It could be very complex. Hyperexcitable cells and
epileptic-type activity are prominent
> Thalamus,
of all the complex interactions, I would first study the interplay
between excitatory thalamocortical projection cells, their target cells
in the cortex, and the inhibitory thalamic reticular neurons that are
fed back upon by the two other types, and in turn inhibit them. Numerous
molecular mechanisms excite and inhibit each of these three players,
creating a number of different stable reverberations, corresponding to
different vigilance states  
> Hypothalumus,
well, there are three main regions, and 10 to 20 different cell groups
(nuclei), and each may contain different types of cells with varied
connections and functions. A few details might be accessible to
intelligent simulation
> Reticular Formation,
It does not exist any more. The former reticular formation consists of
numerous cell groups with very definite connections and neurochemistry,
so be prepared to learn about half a dozen well-defined and well-known
and about 20 less well known small regions (the least defined are still
often referred to as "the reticular core of the brain stem")
> Brain Stem,
In addition to the former reticular formation this contains a lot of
motor, sensory and autonomic nuclei, so there is no such thing as one
type of connection and function
> Cerebellum,
that is a rather regularly wired thing with about 10 main players
> Tectum,
Ah. It is part of the brain stem. Originally a couple of sensory 
reception areas, the tectum also contain elements typical of 
"brain stem" and "reticular formation". 
> Basal Ganglia (Striatum),
Well, it is possible to model the nigro-striatal-pallidal circuits
I am too lazy to try to find out what you mean by that
> (These are, by the way, parts of Non-Mammalian brains. I don’t know what
> differences there are with mammals)
I, on the other hand, referred only to mammals, so with the exception of
ADVR (?), we are talking about the same things.

> What I like to know is how do the neurons work individually in each of these
> parts, and how do they
> interact with each other (how are the networks put together).

My point was that this is a vast subject, more complex than you seem 
yet to appreciate, and you had better start by reading one of the 
excellent textbooks that people have been suggesting.
  When you have selected something that seems reasonable to try to
actually model, you will do wisely in also appreciating that no neuron
reacts in a deterministic fashion to input stimuli. The impact of 
each type of stimulus on the neuron is constantly modulated by numerous
factors in the input terminal, in the target cell membrane, in the
target cell cytoplasm, and in the target cell nucleus, with the result
that the end result - action potential or not - is a probabilistic
function of, modestly put, a hundred major players in that cell.
  Still, it would be nice to know what could come out. Perhaps we can
have a followup in ten years from now?

Dag Stenberg
Dag Stenberg     MD PhD                    stenberg at cc.helsinki.fi
Institute of Biomedicine		   tel: (int.+)358-9-1918532
Department of Physiology                   fax: (int.+)358-9-1918681
P.O.Box 9        (Siltavuorenpenger 20 J)   
FIN-00014 University of Helsinki,Finland   

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