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Sundowning: severe dementia and bringing on the night (corticosterone increases aggression in the rat)

KP-PC k.p.collins at worldnet.att.net%remove%
Thu Apr 3 22:08:17 EST 2003


Hi Didier.

"Didier A. Depireux" <didier at rai.isr.umd.edu> wrote in message
news:b6hj3t$e9q$2 at grapevine.wam.umd.edu...
| In bionet.neuroscience KP-PC <k.p.collins at worldnet.att.net%remove%>
wrote:
|
| > |The brain could theoretically work with
| > | almost no entropy change.
|
| > Not True.

I stand on my "not True" in reply to the prior post.

| Well, that would depend on what is meant by "almost". After all, as
you form
| new memories, no change is observed in the brain's structures etc.
Looking
| at the organism as a whole, you see that new memories/abilities are
being
| formed, but looking at the single neuron level, you don't know what
changes
| occur (and don't tell me that LTP is a model for memory).


I agree, Didier, and here's why: The 'problem' is that the
microscopic trophic modifications to the neural structure as a result
of the neural activation that occurs within it are distributed
throughout the neural Topology. This results in any attempt to
observe energydynamics that are restricted to any relatively-small
'area' [say, and individual neuron's structure] turning up 'no'
correlations that can be said to specifically encode learning -
because, while one thing happens at this 'time' a contrary thing
happens at other 'times'.

But, when one steps back, a bit, to use more-structurally-inclusive
methodologies, as one does so with increasing structural inclusivity,
one sees, plain as day, that the overall neural Topology is
undergoing net-modification as the direct result of the neural
activation that has occurred within it.

Easy [gross neuroanatomical] examples abound, the most-striking,
perhaps, being examples of neural plasticity following episodes of
stroke, or limb amputation, etc.

The 'memory' problem has been deemed to be 'difficult' because
experimenters have applied the vast armada of "molecular"
experimental techniques within a problem 'area' that is inherently a
complexly =distributed= one, It's an instance in which technological
prowess hinders, instead of helping - because, look too closely, and
what one sees seems to be 'without correlation'. But as one looks at
the problem with increasing distributed inclusivity, one can easily
see the net distributed modifications that occur as the result of the
neural activation that has occurred within the system.

This distributed solution is old, dating back to Karl Lashley's
thirty years of searching for the "engram". His principles of "mass
action" and "equipotentiality" are solid-gold stuff - they set the
Standard for resolution of the "memory" problem.

It's because the micro-mods [the "biological mass" which instantiates
"behavioral inertia"] are =distributed= within the ever-changingness
of the global neural Topology.

We can see the single-neuron modifications, we just cannot see their
correlations to "memory" unless we 'step back' to "see the forrest
[despite] the trees" :-]

Cheers, Didier, ken

|
| Didier
|
| --
| Didier A Depireux         ddepi001 at umaryland.edu
didier at isr.umd.edu
| 685 W.Baltimore Str
http://neurobiology.umaryland.edu/depireux.htm
| Anatomy and Neurobiology                      Phone: 410-706-1272
(off)
| University of Maryland                                      -1273
(lab)
| Baltimore MD 21201 USA                             Fax:
1-410-706-2512





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