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From: ada612@csc.anu.oz.au
Newsgroups: comp.ai
Subject: Re: simulating brains
Message-ID: <1990Sep26.202658.2906@csc.anu.oz.au>
Date: 26 Sep 90 10:26:58 GMT
Organization: Computer Services, Australian National University
Lines: 28

From <1292@fornax.UUCP> miron@fornax.UUCP (Miron Cuperman)

>What is a sufficient condition for a simulation of a brain to be good enough?
>The noise induced by the finite precision of the simulation must be on the
>order of magnitude of normal noise we experience.  If that is so, the
>simulation is adequate.

Reflecting on my original question, this seems right:  since neural
behavior is sloppy and imprecise, the roundoff errors of fixed precision
digital simulations shouldn't make any difference to the quality of
performance.

>Brains MUST be equivalent to finite state machines.  Any precision beyond
>the energy of natural noise has no influence.
>
>Conclusion:  Brains are finite state machines with noise.  Therefore there
>is no a-priori reason why they cannot be simulated.

But this seems wrong, because brains can also *grow* while they operate,
which is not something that finite state machines can do.  Turing
machines on the other hand can grow in the rather limited sense that
they amount of tape they have written on can get larger, but brains
can add new active computational agents, in the form of synapse connections.
This is clearly a more radical form of extensibility (if you're interested
in what can be done in real time).


Avery Andrews  (ada612@csc.anu.oz.au)