machine brains

Malcolm McMahon malcolm at pigsty.demon.co.uk
Mon Mar 8 13:17:05 EST 1999


On Mon, 08 Mar 1999 09:21:19 -0500, Michael Edelman <mje at mich.com>
wrote:

>
>
>Malcolm McMahon wrote:
>
>>
>> But it _is_ pretty clear what constitutes wiring and what constitute
>> transient electrical states in that wiring.
>
>But that still doesn't tell us what's program and what's data.

Indeed, as a programmer I don't believe that there is any firm
distinction. Data is more volatile. That's about it.


> Changes in wiring may be
>actual axonal growth, or it may be long-term potentiation of synapses. And axonal growth
>may be repair, not memory change.
>

True, and dendritic growth is another aspect. In fact the latest news is
that new neurons actually grow in mature rats' brains contrary to
previous orthodoxy. But I don't have much doubt that a lot of these
changes are related to learning.

I suspect there's something ressembling an evolutionary process going on
in the CNS with neurons, dendrites, axions and synapses all forming more
of less at random all the time and then dying back if they fail to
justify their existance.


>
>ECT typically affects LTM as well, and I don't think it's accurate to say it "completely
>scrambles the electrical state of the brain". It doesn't scramble it at all- rather, it
>synchronizes it, much as occurs in a seizure- which is where the idea for ECT came from.
>

I think it's probably pretty much like when your PC locks up and you
switch it off for long enough for the capaciters to discharge, then
start it up again.

Of course it's also known to do some actual brain damage so it's not
surprising than LTM is somewhat affected.

>The point still holds that we cannot distinguish structure from content, or program from
>storage, in the brain; is a particular "wiring" the matrix on which a memory can be stored,
>or is it the memory itself?
>

That's what I'm saying.

>>
>> But our only awareness of consciousness is inherently subjective. We
>> can't perceive consciousness, only experience it.
>
>There's that tricky "we" again. The point is that we all do experience conciousness. To
>call it epiuphenomenal as some do is to define away an essential characterisitic of the
>brain.

I certainly don't dismiss its existance, only that it can be observed
other than subjectively.




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