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machine brains

Michael Edelman mje at mich.com
Thu Mar 4 08:34:04 EST 1999

Malcolm McMahon wrote: ....

> >
> >I think your analogy with computer hardware and software is appropriate.  I think
> >of the mind (teehee!) as a set of programs, and the brain as the hardware.  You
> >can always change your mind, upgrade it even.  And you can tune your brain with
> >drugs and sensory deprivation.
> It's important to remember though that the "wetware" actually changes
> the topology of the brain. It's more like an analogue than a digital
> computer in this respect, it rewires itself all the time.
> There isn't the clear distinction between hardware and software that
> characterises the digital computer.

Is there in fact a clear distinction in digital computers? Other than the fact that we
know, a priori, that programs have to be loaded into computers, the distinction isn't
really clear. To an outside observer the program is a essentially description of the
state transitions in the digital computer. It's not clear what constitutes program and
what constitutes data except by prior knowledge of the history of the program. For
that matter, if we look closely enough, a digital computer consists of a very large
number of analog elements that, if viewed at a higher level of functional abstration,
appear to be operating in the digital domain. In other words, the digital computer
looks like an analog device at the individual transistor level, a digital device at
the gate level, and an abstract state machine at a higher level.

The brain similarly looks like an voltage-based analog device at the level of the
neuron, and a rate-responsive device at a higher level. At some very high level it
looks rather like an intelligent entity. Nonetheless it could theoretically be
described at any instant in time by a very large set of differential equations that
would predict what the voltages would be in the next millisecond.

> And, BTW, I still don't see any reason to believe consciousness is part
> of the mind.

That strikes me more as a definition than as a statement regarding function. Does
conciousness exist? Well, we all certainly have the phenomenological experience of
conciousness, and we believe that others do as well, and all act in our day to day
lives as if we and others do. That certainly suggests not only that  conciousness is
an important enough phenomenon to study, but that it is possible to study it in
objective ways.

Michael Edelman

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