X-Message-Number: 5835 From: (Thomas Donaldson) Subject: Re: CryoNet #5707 - #5709 Date: Mon, 26 Feb 1996 12:12:09 -0800 (PST) To Ralph Dratman: So far as I understand cryobiology, IN THEORY a very fast freezing would be appropriate. But no one has come even close to working out how to freeze a human head fast enough; in practise it is a non-question. Obviously if we can't do it we have no way of testing it, one more reason why it is a nonquestion. Who said that our theories will be correct? The best practical way to suspend someone is to freeze them slowly and over a longish period. In real suspensions, they are frozen first to below 0 C, and then an automatic system ramps them down slowly over several days. (At one time that system wasn't automatic, some real person had to watch over the patients; but Hugh Hixon and Keith Henson (I believe) successfully worked out a way to automate that phase). One of the major real questions we are trying to deal with now has 2 "phases": first, we want better solutions for taking someone down to freezing level. Such solutions must protect patients against the effects of ischemia, for instance. Second, we want better solutions for long term storage. Right now, in my book, the best work on this second phase is done by Greg Fahy, who is a professional (PhD) cryobiologist and has been developing means to vitrify kidneys rather than freeze them. Since virtually all the damage due to freezing comes from crystallization of the ice-solution mixture, finding a way to make itturn into a glass would cut that damage WAY down. In terms of whether or not such techniques will preserve our memory, I will say this: the current ideas about memory held by most neuroscientists would say that our memories are encoded at the level of a cells, not in specific molecules. (A light microscope of high magnification could verify that memories were or were not present). To recover memories from a brain damaged by freezing, ischemia, and all the other things that would damage brains will very likely take examination on a molecular rather than a cellular level. There seems to be someone on Cryonet who would be happy to be revived with no memories of his previous life at all. That can be easily done right now, though most of us want much more than that to be preserved. Still, each to their own. Best and long long life, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=5835