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brain/body size and intelligence

John H. johnhkm at netsprintXXXX.net.au
Wed Nov 10 03:12:20 EST 1999


JoshCahoon <joshcahoon at cs.com> wrote in message
news:19991109222622.06753.00003687 at ng-fr1.news.cs.com...
> .>within this 'equation', big bodies require comensurately-big nervous
systems
> >be-cause they have to signal longer distances within that bigger body,
which
> >means that neruons have to be larger so that they can contain larger
versions
> >of the energy-transformation stuff that empowers neural activation
dynamics.
> So blue whale have huge neurons? And rat neurons are puny? And ours are
> somewhere in between?


Myelin sheathing overcomes some transmission problems, some axons are very
long. I don't see why you need a "larger version" of the "energy
transformation".  .

Body size in itself may not be real problem. Larger nervous systems,
particularly those well endowed with associational cortices, require
over-arching mechanisms to keep all that under control.

Decreasing CNS size does roughly correlate with smaller neurons and greater
density. Birds are the most dense in this respect I believe.



> Even if that is the case, it seems to apply significantly only to motor
and
> sensory cortex.  The size of the body doesn't result in association cortex
> having to communicate across longer distances.






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