X-Message-Number: 4483
From:  (Thomas Donaldson)
Subject: Re: CryoNet #4480 - #4481
Date: Wed, 7 Jun 1995 18:14:05 -0700 (PDT)


To Mr. Leitl:

You may wish to check this with organizations which are actually performing
cryosuspension. However, as I understand it, freezing a brain separate from the
skull enclosing it is very difficult due to the fact that brains get their 
blood from vessels that come in from outside. This means that it has proven
very difficult to remove a brain without also cutting major blood vessels, thus
making perfusion impossible.

It is certainly true that even the storage of heads is (if we want to save 
the information in that head) much more efficient than storage of a whole body.
Some kinds of learning (motor learning of rote tasks) do occur in our upper
spinal cord and may have to be relearned upon revival if you are stored as

a head. A ballet star, therefore, may want to carry along their spinal cord too,
at a minimum. To my knowledge no one has actually asked for that. Removal of a 
head, of course, leaves much more than simple cosmetic damage. As I understand
some families of suspension patients have proceeded to bury the body and hold a
funeral service, regardless. For most Christian sects, a body need not actually
be present for a funeral service.

In any case, the only instances in which brains have been frozen separately 
werecases of very damaged patients, often after autopsy, in which the brain 
were gathered together and frozen without cryoprotectant (since at that time 
it had been too long, and cryoprotectant could not be perfused into the brain).

Furthermore, in terms of MOTIVATION, there are quite good reasons to believe
that loss of a body will someday be repairable independently of any issues of
uploading. The basic strategy such a repair would follow would be to guide
the regeneration of the body using the chemicals and knowledge of development
and how it works. The patient would be unconscious while this happened. Our
ability to carry out such radical repairs, including (naturally) repair of 
severed neural connections etc, has been masked rather than eliminated totally
when we became mature. (The same may be said of brain repair itself).

If you do wish to preserve a brain for uploading specifically (I personally
think that is making too many assumptions about the future, and would suggest
that it would be far safer to provide future doctors (? whatever they will be

called) with everything possible. In any case, glycerol has uniformly turned 
outto be a better cryoprotectant. Proposals for some variety of embalming (which
would basically fix the brain tissues) have so far run against the problem that
it is very hard to get the fixative to penetrate the brain completely; if that
problem were to be solved, it may provide a solution to anyone who wants to 
preserve the required information about him/herself. I don't know of anyone
actively working on this problem, however.

As for the actual computer readout of a preserved brain, one problem with
present methods of cryopreservation is that they cause damage. This damage may
or may not destroy information. I will say, however, that reasonably assured
means of preserving the information (as distinct from preserving viability of 

individual brain cells or the brain itself) are likely to come much earlier 
thanany means to preserve not just information but viability. In that sense, 

you need may become available before full suspended animation. (Many 
cryonicistswould feel that such an advance basically settled any question about 
whether or
not to be suspended). Of course, the means by which such readout could be done
can be speculated about, but if your brain persists for some time, much better
means than we can currently imagine will probably become available. I can 
suggest elaborate biochemical means, for instance, which would require a 
biotechnology well in advance of what we have now but which also would read out
your brain NONdestructively.

(A short summary of how such a system would work: You have two separate kinds 

of specialized bacteria, perhaps viruses. The first enters you brain and then   
labels each neuron (and astrocytes too, if they prove to play a significant
role). A second variety then enters your brain as one single organism. In 
each neuron (or close to but outside it) it works out what the connectivty
of that neuron is, then modifies a long DNA string to mark down that 
connectivity. Then it creates N copies of itself, where N is the number of
neurons (astrocytes?) to which the first neuron connects, and sends these
copies to each connecting neuron. Finally after all of these are done, they 
are drawn from the body of a patient and the information is assembled in a 
computer. This scheme assumes that long term memory results from nerve 
connectivity, but if it results from some other factor, that can be encoded
just as easily. Incidentally, schemes very similar to this have been used and
are being used to map out a message passing parallel computer by software 
which may not know what its structure is. The information which each of these
engineered bacteria need to carry would not be large).

			Long long life,

				Thomas Donaldson

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