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machine brains

Michael Edelman mje at mich.com
Fri Feb 19 11:39:26 EST 1999

Ray Scanlon wrote:

> Michael Edelman wrote in message <36CC6078.4BC546AD at mich.com>...
> >
> >
> >Ray Scanlon wrote:
> >
> >> ...
> >>
> >> I do not think of the computer as a model for the brain. I think of the
> >> brain as a network of leaky integrators.
> >>
> >
> >....which is to say, as an analog computer.
> Of course! But with individual neurons having highly non-linear input and
> spectacularly non-linear output. The output of the brain to the motor
> neurons is essentially digital.

No, not at all. While an AP is an all-or-nothing event, what matters is not
the individual AP, but the overal activation level. In the case of afferent or
efferent neurons the salient feature is rate. Faster firing, more input or
output. It's analog, and the main efferent coding is pulse rate.

To say it's digital is to say that there's an arbitrary symbolic encoding, but
so far I don't think anyone has established that.

Michael Edelman     http://www.mich.com/~mje
Telescope guide:    http://www.mich.com/~mje/scope.html
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