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machine brains

Ray Scanlon rscanlon at wsg.net
Sat Feb 13 21:44:26 EST 1999



Sylvanian wrote in message <36C4DE33.347991DE at hotmail.com>...
>Stephen Mann schrieb:
>
>> Ray Scanlon (rscanlon at wsg.net) wrote:
>>
>> : only neuromimes. As a first step we examine the brain to see how the
neurons
>> : do these things. If we can explain the how the brain thinks, how it
decides,
>> : we shall know how to design the machine.
>
>The drawback is certainly that, using cerebral neuronal structures as a
fundament
>for intelligence, the transfer of their functional parameters to a
>microelectronical device would be very difficult.

What do we wish to simulate and at what level? Are we talking, for instance,
of the brain of rat? This is a mammalian brain, it has all the parts of a
man's brain, just not so many neurons? What is the unit of our simulation?
The neuron?

The neuron is a large assortment of neurons, I have no idea how many. I
would be happy if someone would give me a guess or a citation as to how many
in an average neuron. Some would say that until we know the story of every
molecule we cannot simulate a neuron. This is hogwash.

What we simulate is what interests us. We are interested in the neuron as an
electromechanical device that influences other neurons. The myriad of
molecular activities that have to do with the maintenance of a living cell
are not involved. The endless molecular activity of a synapse can be lumped
together with a few parameters. The synapse is strengthened or it is
weakened. The synapse disappears. there is axonal growth and new synapses
appear. All these are subject to a time dependence (from birth to death of
the organism). A synaptic event involves a local change in the potential
difference between the interior and the exterior.

This is not very much as simulation goes.

We can go as far as we want in detail until the simulation of three or four
neurons is a major enterprise, Or we can do a lot of lumping together until
we have the entire neuron as a leaky integrator.

We can take the nuclei and  Brodman's areas as our units and simulate them.

There is no problem as long as we keep the soul (mind) out of it. The brain
is simple and its activities are simple. We are overwhelmed by the number of
neurons, by the number of nuclei, by the number of tracts, but if we lump
the trees together we shall see the forest.

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










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