X-Message-Number: 16225 Date: Mon, 7 May 2001 11:10:19 -0400 From: Thomas Donaldson <> Subject: CryoNet #16213 - #16220 Hi again! About stem cells: they have been studied now, with significant progress, for several years. We may yet see their use in repair. However the major issue for cryonicists isn't the repair of organs, or even the repair of SOME brain regions, but the repair and recovery of memory in our brains. Even worse, for some time neuroscientists have generally believed that our memories were stored in the connections (at a low level) of our neurons. Although this work has hardly received the interest that work on stem cells has, there are two strains of research which may show that this common theory has some big holes. Just how we'll fix those holes remains unknown, but they are certainly present and need attention. First, we grow new neurons even as adults, and these neurons seem to play a role in learning, too. The next-to-latest issue of PERIASTRON talked about this issue in more detail. Note that if neurons grow and disappear, especially in the brains of apes (of which we are one) then we can't just say memory is a matter of connections. There must be additional factors here. Second, connections between neurons at the lowest level (synapses) seem not to be nearly as constant as people once thought. Every time neuroscientists have been able to watch this in action, they've found synapses coming into existence and going out of existence over time. (There ARE hard experimental problems here to doing this, but the stability of synapses does not look very great). Since synapses form the main connections between neurons, their stability or lack of it must tell us something important about memory. Just some scientific comments about how stem cells relate to cryonics. Yes, we'd like to repair our bodies too, but if we cannot recover our memories we are no better than twins born at a different time (what many want to call "clones"). Best wishes and long long life for all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=16225