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machine brains

Ray Scanlon rscanlon at wsg.net
Fri Feb 19 20:45:33 EST 1999



Michael Edelman wrote in message <36CD93BE.A17C476F at mich.com>...
>
>
>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.

My God! I have stuck my finger into the hornet's nest of factionalism. I
have absolutely no use for arbitrary symbolic encodings. I have absolutely
no use for arguments over digital versus analog. I have a particular lack of
use for encodings and labeled lines. Anyway I misspoke. I meant the output
of the motor neurons, not the input. The muscle fibers do not integrate
their input, they react directly.


It does seem useful to view the neuron as a leaky integrator.

Ray
Those interested in how the brain works might look at
www.wsg.net/~rscanlon/brain.html








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