X-Message-Number: 11452
From: Thomas Donaldson <>
Subject: To Jeff Davis, a very short summary of what we know about brains
Date: Wed, 24 Mar 1999 23:28:19 +1100 (EST)

Hi everyone!

To Jeff Davis: 
Basically what you say is probably right. The major way in which memory is
apparently stored in our brain is now believed by most neuroscientists to
consist of the connections between neurons and the propensity of these
connections to respond.

And yes, some major brain structures important for brain FUNCTION may not
be needed for the actual preservation of memory. The hippocampus and other
nearby structures play an important role in at least one kind of memory,
both for learning and for recall. But their preservation of memory, aside
from a period of several days (with a gray area on just how long) is not
involved in true long term memory ie. all the connections in other brain
areas which form the permanent memory. This suggests that total loss of
a hippocampus would not really affect storage of information, and by
replacing those structures we would recover the person.

But there are many other kinds of damage. Alzheimer's Disease ultimately
destroys the brain cells generally (though it at first attacks particular
areas). Ultimately the person becomes unrecoverable. Multiple small
strokes can wipe out memory, though their exact effect depends on exactly
where they occur. The structures which apparently contain memory of one
kind or another SEEM to consist of the brain cortex generally and part of
the cerebellum.

I put together a bibliography on memory and how it works at the level of
neurons and brains which I can send to you if you wish (by email). You
will note that in this Cryonet, I have another message pointing out that
nanotechnology will not solve all problems. To recover a damaged person
(or alternatively show that they are irrecoverable) may well require some
form of nanotechnology, both for the recovery and to investigate just 
what has happened. But for both purposes we will also need to know more
than we do now about brain structure and activity, both for healthy
brains and for damaged brains. 

And if you get REALLY interested, I publish a newsletter which discusses
such things, in the special context of cryonics. Yes, the newsletter costs
money while the bibliography is free.

			Best and long long life,

				Thomas Donaldson

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