question: job of a neuron

Richard Norman rsnorman at mediaone.net
Sun Sep 9 12:07:48 EST 2001


On Mon, 10 Sep 2001 00:30:05 +1000, "John H" <John at faraway.com.au>
wrote:

>Thanks for the evolution lesson. Reading today a basic neuro primer (layman,
>reads journal articles while reading primers) the author stated that in
>humans interneurons occur in very high numbers relative to other animals. I
>believe Matt that you have done research into GABA(still are?) and wonder if
>you can provide any insight into the idea of this high density of
>interneurons. If true, why, what is so special about human brains that we
>would require so many interneurons?
>

There are sensory neurons, motor neurons, and interneurons.  The
number of motor neurons depends on the size of the animal and the
number of muscle cells (actually, the number of motor units) that must
be activated.  And humans are no different from other animals of
comparable size in motor ability.  Similarly, the number of sensory
cells depends mainly on the acuity or fineness of resolution (size of
the receptive field) of each sense.  Again, humans are no different
from other animals in the evolutionary need to be able to recognize
and detect objects in our environment.  So, if we indeed have large
brains (which we do) it is necessarily because of the number of
interneurons.   And it is probably not so much "why do we require so
many interneurons" as "what are we capable of doing now that we have
so many interneurons"?




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