X-Message-Number: 5219 From: (Thomas Donaldson) Subject: Re: CryoNet #5182 - #5190 Date: Sun, 19 Nov 1995 10:15:02 -0800 (PST) Hi again! A brief point about brain transplants. They are being tried now for Parkinson's disease, and there have been some work on using them for memory loss also (not to replace the memory, but to replace some of the brain circuits which do the remembering). The trick is to use embryonic brain tissue ---- although I would also comment that if we knew how to flip the development switches that make the difference between embryonic brain tissue and adult we would then know how to use adult tissue (and neuroscientists also work on that issue, too). In some cases the implant helps simply because it is there to produce the right level of acetylcholine. (Inside our brains acetylcholine seems to act not as a transmitter but simply as a stimulant). In other cases, actual connections are needed. In such cases, the transplanted tissue will often grow directly to the right spot (if it comes from a similar place in the embryonic brain). This work, among other interesting results, also tells us that work on brain development (and not just on how memory works) may also turn out to be important for cryonics. In some cases, we won't have to work out how to reconnect: it will be there in the development program of the neurons. It's only our relatively primitive level of understanding about how brains and bodies grow that make such questions seem to be problems which must be solved by direct force (which incidentally, in brain repair, has been tried many times without success). Best and long long life, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=5219