X-Message-Number: 12176 From: Thomas Donaldson <> Subject: To Doug Skrecky: comments on dispensable brain areas, and others Date: Fri, 23 Jul 1999 22:36:18 +1000 (EST) To Doug Skrecky: The scientific standard of your postings has gone up a good deal since you first started several years ago. I've found several of your postings quite useful. However your message suggested something about how a brain is usually preserved, something quite false. Because the vascular system for a brain comes in from the outside, if we try to remove it from the skull we're risking lots of damage to the very system we'd use to perfuse cryoprotectant. The only cases in which brains have been preserved for cryonics while not preserving the head have been cases in which the brain was already damaged so much that it could not even be perfused with cryoprotectants in the first place. TransTime, for instance, did that with the brain of a 15 year-old murder victim. As to whether it makes a difference whether or not you choose to be preserved as a head alone, or as a whole body, I'd say the jury is still out on that one. My personal opinion is that if we can revive a head cryopreserved with CURRENT methods, then we'll be able to make it grow a new body too (the first is much harder than the second). That situation may not continue if the work on improved methods of cryopreservation in cryonics proceeds... at least for those fortunate enough to be able to use such work (the fate of the murder victim would not be affected by advances in cryopreservation, and other less spectacular misfortunes can also happen ... cryonics is emergency medicine, after all). I actually hope that it does not continue, if only because it would be very good to know that our brain would remain intact and revivable. One other issue about preservation of a complete brain: it is one thing to grow up with half a brain, and quite another to have half your brain removed when you are an adult. That latter case will cause damage, depending on just which hemisphere is lacking. Yes, the missing hemisphere might be added, complete with connections, but somehow even then there remains the issue of just what parts of personal memories may have been lost. At the same time, if we look closely at the function of different areas in our brain, it's quite clear that some areas, particularly lower areas such as the amygdala, might well be recreated afterwards with no loss at all. (I"m not saying that our amygdala isn't important, just that it may depend much more on our genes rather than our experience, and therefore be easily recreated). A full understanding of how brains work is likely to show up many brain areas which we hold in common and which therefore need not be preserved to preserve a person. The major nerve tracts in our brain provide a second example: though it's unlikely that they could be removed, their repair might only require copying a standard pattern... or at most, a pattern gotten from the genes of the patient. Again, some areas which even I would have once thought were dispensable (in this special sense: easy to replace, NOT dispensable in a person awake and living in the world) such as the cerebellum turn out to contain memories, too. And there's some chance that even our hippocampus, which seems mostly to act as a "door" for letting memories in and reading them out, may hold its own special memories. Best wishes and long long life, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12176