Re: Neural Nets

From: Marshall, Helen (
Date: Fri May 24 1996 - 11:32:59 BST

Question 37. What is the evidence that neural nets are like
the brain?

Neural nets can be constructed physically but are often
simulations because what is important is that they do what
we do, not do it in the same way we do it. However, for
nets to give a realistic impression of what we do they
should have similarities with the brain because our
cognitions occur in our brains. Nets are like the brain in
several ways, for example, both have interconnected units -
in the brain these are neurons which send messages across a
synapse and in nets these are connecting nodes; both have
positive and negative connections which means that the
neurons/nodes can have either excitatory or inhibitory
effects on surrounding ones. Both nodes and neurons pass
activity to each other. The brain does this through action
potentials and nets do it via a transfer function which
means spreading activation, i.e. when one node is activated
it brings those it is connected to into a similar state of
activation. This process is called propogation. Also, like
the brain, the connections in nets can become weaker or
stronger and can be coded locally or in a distributed way.
A final similarity between nets and the brain is they both
have the ability to learn new things.

However, there is evidence of differences between the brain
and nets. For example, nets are arranged in layers but the
brain is not and they are very different in terms of
biology. Also, nets are not efficient at logical reasoning
or language whereas the brain can cope with these well.
Nets are similar to the brain in some respects but not
others so perhaps as we learn more we can develop them so
that they can do more of the things we do.

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