X-Message-Number: 12620
From: Thomas Donaldson <>
Subject: synapses do NOT each carry a single bit
Date: Sat, 23 Oct 1999 22:24:46 +1000 (EST)

To everyone:

Unfortunately, our neurons and our brain look much more complex than 
simply one bit per synapse --- or whatever. 

First of all, synapses aren't always permanent, and neurons grow and 
lose them constantly. Second, synapses do not simply act to STORE
memories; once their activity has increased, then they act as part of
our brain circuitry to express ... something ... (since individual
neurons are involved in many different activities). The really important
thing to remember here is that neurons aren't passive storehouses of
memory, they are constantly active. They work more like individual
processors than like memory chips; and since they are biological, that
activity can involve growth and loss, too ie. growth of new synapses,
loss of others. This has actually been observed. (If you want me to
cite references, I can send them separately). Moreover, the changes in
synapses means that no single synapse really represents a single bit.  

I will add here that these features do NOT mean that the informational
view of us as distinct from the physical view is false. They do say that
we're not dealing with something which easily fits into any existing
computer model, including the neural nets which have now come into
wide use. Nor is it fundamentally impossible to create neural nets
similar to those in our brain. It just hasn't yet been done. We may
very well, eventually, be stored as patterns of information only; but
realizing that pattern of information in anything like present computers
would be unnecessarily involved and difficult, and perhaps even 
impossible because such devices cannot imitate brains closely enough.
(An analogy, to explain this point: we cannot make airplanes if we
insist on using wheels only. At some time or other we'll need to make
and use WINGS). 

			Best and long long life to all,
				Thomas Donaldson

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