IUBio

The Survival of the Wittiest

yan king yin (dont spam) y.k.y at lycos.com
Wed Jan 16 08:44:03 EST 2002


Thanks for posting about Edelman's theory. I have been following
some research that might be related to it.

For example, there is the recent finding that in the hippocampus,
new cells are generated at the rate of 5000 neurons per day. Many
of them do not survive. One wonders what these new neurons are
doing?Could they be eliminated by selection?

There is also speculation of new neurons in the primate cortex, I
guess this issue is under investigation.

As for Darwinian selection at the synaptic level, I have read that a
strictly eliminative view (where no new synapses are generated) is
unlikely to be correct. But there could be both generative and
eliminative processes. During the development of the brain, synapse
density peaks at about postnatal age 3 or so (dont have the book
here) and it reaches a form of plateau until a gradual decline towards
old age. This pattern is not entirely congruent with an eliminative
view.

I think more evidence is needed to decide the validity of his theory.
I would be very interested to know of such progress.






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