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From: warren@sniff.UUCP
Newsgroups: sci.bio,sci.med,comp.ai,sci.misc
Subject: Re: Neurons can't regenerate? (was: Re: Taking AI models...)
Message-ID: <333@sniff.dec.com>
Date: Sun, 14-Jun-87 20:11:40 EDT
Article-I.D.: sniff.333
Posted: Sun Jun 14 20:11:40 1987
Date-Received: Mon, 15-Jun-87 05:37:38 EDT
References: <622@unicus.UUCP> <1331@sigi.Colorado.EDU> <1349@sigi.Colorado.EDU> <1757@ttrdc.UUCP>
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Xref: utgpu sci.bio:373 sci.med:2086 comp.ai:483 sci.misc:282

In article <1757@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes:
>In article <1349@sigi.Colorado.EDU>, eddy@boulder.Colorado.EDU (Sean Eddy) writes:
>> ...there are cells that do not
>> divide after a certain point, yet still age and die. Neurons are the
>> classic example; not only do they not divide, they cannot even
>> be replaced (in humans) if damaged.
>
>Am I misinformed, then, when I hear about nerves growing back together in
>people who have an accidentally severed appendage surgically reattached?
>Also, what about the nerves which grow back into a wounded region of the
>body, say an area of burned flesh?
>-- 

No, you are not misinformed.  Damaged nerves can heal but only to a very
limited extent.

So you're both right.  In Seans case Neurons do die and are not replaced
through normal cell division.  However, the brain is so..... redundant
that you could kill off billions of Neurons and very possibly never no
it.  Wars have historically been very beneficial in gaining insights into
brain (Neuron) function.  Also, in a classic experiment called the Island
Experiment a monkey (I think) was taught a particular trick.  The monkey
underwent a series of operations each one of which removed a piece of 
the monkeys cortex.  To everyones surprise, in the end, when all that was
left was a little island of cortex; the monkey could still do the trick.

In your case Daniel, you know that there are different degrees of 
burns.  Small amounts of nerve damage from small burns can be tolerated.
However,  you must also know that severe burns cause irreparable damage
to nerves.

Think about this the next time you have a beer. The alcohol, it is said,
kills Neurons.  :-)  :-)

A good book to read for those interested in the brain is "Mind and
Supermind" by Albert Rosenfield, Holt Rinehart Winston.  It's easy
reading and very interesting.

Warren  (an amateur doctor at best)