X-Message-Number: 10421
Date: Sun, 13 Sep 1998 08:57:49 -0400
From: Thomas Donaldson <>
Subject: CryoNet #10415 - #10418

Hi everyone!

I want to thank Jeff Davis very much for his references. It's not clear
that our memory STORAGE uses these methods, but I've taken his references
and will get and read them.

The major point about "scrambled salamander brains" is important and simple.
Current ideas about how our memory works suggest that it is encoded in the
connections between neurons, quite possibly by the growth or splitting of
synapses. This is a fine idea, and probably contains a kernel of truth.
However neurons also turn out to be very active, and in those few cases
in which identified neurons could be followed for several weeks in living
animals, the experimenters found that even the synaptic connections changed

I will have to leave the matter at this level, for no other reason than 
that its relation to long term memory is now quite unknown. Such
observations suggest but certainly do not prove that there is more to long
term memory (I mean memory that lasts for years) than simply the nerve
cell connections. And that for our own purposes it would be very important
indeed to find out just what that "more" may be. Within an individual
neuron there might be, for instance, some chemical which increases the
general level of connectivity of it with another (this may be an activity
which works between them, not one that happens in both in some isolated
way). When our brain forms in embryo, different neurons actually grow 
towards their targets. These targets apparently are not at first defined
precisely, but the neurons aim to connect with others of some particular
type and location. It may prove useful to learn much more about such 
growth, with the idea that it just might give clues to how connectivity 
might persist while the synapses which implement it at any given time
change constantly. 

It's a major problem with this idea that following individual neurons in
living animals is not at all easy. It could even be that the observations
that found this constant change did not generalize to other brain areas
at all. There is more to this, still, when we consider cryonics. If the
actual connectivities (I mean the actual synapses and their location)
are not primary here, then that could mean that even if we revived a
brain, and restored its connectivity, we could discover that it changed
and disappeared after only a short time. Why? Because whatever influences
maintained it prior to suspension were not restored, only the connectivity
was restored. 

If I were to try to follow connectivity changes in the cerebral cortex,
say of a monkey, for several weeks, I would devise an experimental 
preparation such that the apparatus for looking at a restricted area of
the monkey's cortex was surgically implanted early in its life and 
organized so that it would not come off. Ideally this might even be
done before its brain connectivity had developed fully. The idea would
be to make a "window" through which we could watch the changes. Making
such a window, especially one that would not be outgrown, doesn't 
sound easy, but still perhaps could be done. The experiments which 
followed changes in neural connectivity did not look directly at the
cerebral cortex.

One possibility might be to use a slow-growing animal (say one of the 
apes) and periodically replace the window apparatus with a larger one.
It's helpful here that our brain doesn't grow as much as our body, 
though it does grow. This would probably work, but take lots of failed
tries before it was successful. But it would tell us something important.

One major complaint about the use of salamanders is that such animals
have far more abilities to recover from brain damage (actually regrowing
connections) than mammals. However the current sense on this issue is
that our ability at brain repair still exists, though it is frustrated
by various other influences in our brains. By removing these frustrating
factors we might restore an ability at brain self-repair. And repair and
maintenance come awfully close to one another.

In any case, thanks again for the references.

			Best and long long life,

				Thomas Donaldson

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