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From: lyang@scherzo.UUCP
Newsgroups: sci.bio,sci.med,comp.ai,sci.misc
Subject: Re: Neurons can't regenerate? (was: Re: Taking AI models...)
Message-ID: <21217@sun.uucp>
Date: Tue, 16-Jun-87 13:46:29 EDT
Article-I.D.: sun.21217
Posted: Tue Jun 16 13:46:29 1987
Date-Received: Thu, 18-Jun-87 02:31:35 EDT
References: <622@unicus.UUCP> <1331@sigi.Colorado.EDU> <1349@sigi.Colorado.EDU> <1757@ttrdc.UUCP> <333@sniff.dec.com>
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Reply-To: lyang@sun.UUCP (Larry Yang)
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Xref: utgpu sci.bio:384 sci.med:2093 comp.ai:496 sci.misc:288

In article <333@sniff.dec.com> warren@sniff.dec.com (warren sypteras) writes:
>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:
>>> [ statement about neuron death ]
>>
>> [ statement about nerve regeneration ]
>
>No, you are not misinformed.  Damaged nerves can heal but only to a very
>limited extent.

As state before, if a nerve is severed and the cell body remains alive, then
that nerve can regenerate and grow new connections.  However, if the cell
body is killed, then that's bye-bye for that neuron.

As an aside, there are cells in the brain that do undergo reproduction. 
These are the cells that mutate into cancerous cells. (aka brain tumors)
An interesting area of cancer research involves understanding why
neurons don't reproduce; what inhibits the cell division process in these
cells?

>
>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.
>
There are two common conclusions that can be drawn from experiments like
these.  One is "information in the brain is reproduced, and only a small
amount of the brain need be retained."  This conclusion is the one you cite.
The other conclusion is "we didn't actually remove the part of the brain
that contains the information on doing learned trick."

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

Actually, alcohol kills the 'dumb' cells first; thus, you should always
get trashed the night before an exam. :-)

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