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Right visual field to left hemisphere. Why?

Matt Jones jonesmat at ohsu.edu
Mon Oct 5 12:17:34 EST 1998


In article <barnes.183-0110981901060001 at pc318.psy.ohio-state.edu> Cosimo,
barnes.183 at osu.edu writes:
>Basic stuff, we all know that the left hemisphere gets sensory info. from
>the right side of the body and sends motor commands to the right side of
>the body and vice versa for the right hemisphere.  Someone hits me with a
>pretty good question the other day.  Why are we like this?  What advantage
>does this wiring system have over simply wiring left to left and right to
>right?

One adaptive advantage can be seen by considering a really simple,
freely-moving organism, with just rudimentary vision. A simple fish, or
planarium or something. Chances are that this organism mainly uses vision
to avoid being eaten by bigger organisms. Because of the mechanism that
the animal uses for locomotion (i.e., it wiggles its body back and
forth), to avoid an object in its right visual field, it needs to
contract the muscles on the left side of its body. A direct connection
between sensory apparatus on the right side, and locomotor apparatus on
the left side would make this escape behaviour much more efficient.
Perhaps this is why vertebrates are organized like this, and we inherited
it from such simple ancestors.

Just a theory.

Matt Jones



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