Deborah and Randall, (01)
I just want to emphasize that points that Randall made
and to add the comment that neuroscientists themselves
are the first to admit three very important points: (02)
1. An enormous amount has been learned about the brain
during the past 30 years. Many of the experiments
show in detail which parts of the brain and even
which individual neurons become active during some
kinds of mental processes. (03)
2. But the more they learn, they discover much, much more
that remains completely unknown. In particular, knowing
what parts become active, does not tell us anything about
what those parts are doing. (04)
3. Many published reports that show how computers "can read
the mind" merely show that it is possible to find correlations
between certain mental activities and activity in certain
parts of the brain. Finding such activity can be a useful
clue to what the person is thinking. But such clues are
similar to what a sensitive person can detect by looking
at facial expressions, tone of voice, gestures, etc.
All of them are clues, but they don't tell us what is
actually happening in the brain. (05)
RRS> Keep in mind that LTP is only one aspect of long-term
> information storage in neuron networks. The topology of
> connections matters, too, obviously. There's probably other
> stuff I'm unaware of or am not thinking of right now. (06)
Some of that other stuff includes the internal structural
and chemical organization of each individual neuron. The
so-called neural networks treat neurons as very simple
switches, and AI systems have obtained some interesting
results from combinations of such switches -- but that
does not imply that those switches are simulating
actual neurons. (07)
Neuroscientists believe that each neuron is far more complex
than a simple switch. A better model might be a rather
complex computer chip or even a complete computer in itself.
But nobody knows what kind of computer it might be or what
kind of code or storage it is processing internally. Even
though researchers can detect the external firing patterns,
nobody has been able to decode those patterns and determine
what kinds of messages they are sending or receiving. (08)
In summary, there's going to be much more information coming
in the next 30 years, but nobody knows when it would be
possible to get a complete simulation of a single neuron,
let alone the complete brain of a fruit fly. Don't even
think of holding your breath waiting for a simulation
of a complete mouse brain. (09)
John Sowa (010)
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