X-Message-Number: 6606
From:  (Thomas Donaldson)
Subject: How to prove brains are working
Date: Wed, 24 Jul 1996 23:48:59 -0700 (PDT)

Hi again!

The notion of vitrifying an animal's brain and keeping the rest of its
body warm enough to support the brain after rewarming is a very unfortunate
furphy.

Here is what I would aim for. We know that we can support the brain with
sufficient blood flow at normal temperature, at least for a short time.
The thing to do then is to stimulate the nerve endings for eyes, ears, etc,
and wire it up for electrical activity. We would naturally want a control
brain that had NOT been vitrified. If we get electrical activity close to 
that of the control, I will consider that one major test has been passed.

There are other lesser tests we can apply (not to the same animal!). The
damage due to freezing, even with cryoprotectant, shows up well when we
look at the tissue with light and electron microscopes. So we do that, too.
Stains for various critical chemicals can also be used. Showing that the
damage was very low after vitrification AND rewarming would buttress any
conclusion we might make from electrical activity.

None of these are tests which involve radically new methods --- the first
one is very much what Suda did in the 60's when he "froze" cat brains.
It seems to me that (after reading Suda's old article again) if we can
get brain activity very close to the control in the situation described
above, then we've basically shown that we can preserve a working brain.
And we can be much more extensive in our testing: say, train the animals to
respond to electrical stimulation of its optical tract (from eye to brain),
with some kind of motion (again, measurable in terms of electrical activity).
Not only don't they involve any radically new methods, but we can probably
do the same kinds of tests much better than Suda could. Work on brains has
advanced quite a lot since Suda.

None of this would be done on human beings, of course. And we may find 
ourselves going to Japan or something to do some of these tests, just because
some people think such experiments are inhumane (no, I wouldn't try to
deliberately cause any pain). There just doesn't seem to be, to me, any
serious problem about verifying the success of vitrification for brains.

			Best and long long life,

				Thomas Donaldson


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