X-Message-Number: 15993 From: "John de Rivaz" <> Subject: Date: Tue, 3 Apr 2001 15:02:59 +0100 Hi, As you probably know there is a long running thread on many newsgroups including sci.cryonics, entitled "Compulsory Post Mortem Dissection" Have you any comments that can be made to this chap whom I have at last persuaded to read the cryonics FAQ? > > (PS: I've read your FAQ and a few other things at your site, I find > > it remarkably weak on the science.). > > What, for instance? This goes into my principle, but hardly my only, reason be believing that cryopreservation won't work. I tried to find whether you had an answer on your site. Maybe I didn't look hard enough. Anyway, the little that I understand of neurology suggests that the operation of a synapse is more than there just being an axon of one neuron near the dendrites (sp?) of another, but the precise positioning of those matter in who the particular connection will behave. When a brain is damaged through lack of oxygen it is not merely that brain cells die, but they become deformed. The tips of the axons change their positions, as to the filaments of the dendrites. Now if the original positions are crucial for the functioning of the brain and the positions change, then the damage is absolutely irreversible unless there is some way to determine the original position. It's like putting a bunch of grains of sand in a box, shaking the box and hoping that future technology will allow some people in the future to put each grain of sand back where it initially was. For simple connections that just echo a signal along a chain of neurons this isn't such an issue. It also may not be a show stopper for invertebrates (sp?) which don't have dendrites. But for big vertebrate brains, it involves damage which is not only permanent by contemporary technology, but fundamentally irreversible because necessary information is lost. Now this is the damage merely from death, and doesn't address at all the damage as a consequence of the actual freezing. Anyway, because information is lost (the exact positioning of the axon terminals with the dendrites) no technology will recover it. Merely saying, as your FAQ does, that we have seen remarkable recoveries from brain damage doesn't address the problem, because there would be no undamaged parts of the brain to take over. The plasticity of the brain at recovering functionality from local damage doesn't address the question of truly global damage to the brain. Even if most of the individual brain cells can be revived (which I very very strongly doubt), to much of the details of the structure is irreversibly lost even before the freezing, but the freezing will probably finish off that job. -j -- Jeffrey Goldberg I have recently moved, see http://www.goldmark.org/jeff/contact.html Relativism is the triumph of authority over truth, convention over justice From line IS valid, but use reply-to. -- Sincerely, John de Rivaz my homepage links to Longevity Report, Fractal Report, music, Inventors' report, an autobio and various other projects: http://www.geocities.com/longevityrpt http://www.autopsychoice.com - should you be able to chose autopsy? Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15993