X-Message-Number: 15344 Date: Mon, 15 Jan 2001 07:39:41 -0500 From: Thomas Donaldson <> Subject: new connections for neurons Hi again! A very brief answer to Mike Perry: The basic theory currently behind how we store our memories would say that we store them in the connections of our neurons. This means that a given connection of neurons would contain a particular set of memories. As I mentioned in my last discussion, this does mean that for a brief time we could have an imitation of a human being with a particular set of memories. However those connections, at least those which are not determined early in life, will be changing constantly. New memories will be acquired and some older memories will be forgotten or modified (consciously or nonconsciously). This means that the imitation of a human being would not last long at all before the real human being it imitates would acquire very different sets of connections. Just how he or she does this does not matter here; the point is that the low figure he discusses is for an instantaneous static picture. If we want to discuss all the different memories such a person may have learned in the past or will learn in the future, we're immediately plunged into factorials such as N!. Forgetting for a moment the really important issue of TIME, the issue here is whether or not a Turing machine could imitate such a machine. Certainly it could imitate the instantaneous static picture, but real persons (and real machines with brains behaving like our own) would quickly differ from their static picture. To work out just what they would come, we must look at all the possible connections they might develop... and so find ourselves among factorials and exponentials. Could the common theory now held by many neuroscientists break apart and be replaced by another one? Well, yes. Ideally we'd want our memories to consist of more than the connections between neurons. Such connections, for a cryonicist, may be very unstable against freezing. In PERIASTRON I discuss some possibilities, but they remain only possibilities. Again, some neuroscientists believe not that we form or lose new/old connections between our neurons but that the connections acquire some features they did not have before the learning. A little thought suggests that such a theory will have its own exponentiality: we have lots of connections but their "weight", say, changes constantly when we acquire new memories. (One major problem with this theory is that experiments have shown a constant formation and destruction of synapses connecting neurons, but that is a long discussion in itself). In any case, this is why I choose N! when I try to calculate the behavior of a brain. In computer terms I am discussing the possible states of a computer, while if we look only at its memory at one time, we get a much smaller set of connections or weights for neurons. That is not a possible state but only one of them, and as such tells us very little about what the computer can do. Best wishes and long long life for all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15344