why are we decussated (crossed over) was Re: Gender and Cognitive Style

From: Timothy Bates (tbates@bunyip.bhs.mq.edu.au)
Date: Sun Nov 22 1998 - 01:24:55 MST


joe said:
>It has also been hypothecized that opposed control has survival
>value; If one is attacked from one side, it is better for the
>sensorimotor complex for that side to be on the other (leeward) side
>so that a head blow would not disable it and it would remain available
>for defence.

deperation. how many attacked ancestors survived when one hemisphere was
disabled by nimbly using the other ;-)

One idea that sounds reasonable to me is that by crossing the input and
output, an organism with paired inputs (ears, lateral line sensors) will
steer towards the signal (moving away increases the ouput of the near
sensor and so steers back on track).

One idea that i had is that all this follows from the fact that the eyes
_don't_ cross over they just course directly back: left of left eye to
left hemisphere etc. That has the unfortunate effect of representing the
right visual field in the left hemisphere: all else follows from this.
 
best,
tim

"The money power of the country will endeavor to prolong its reign by
 working upon the prejudices of the people, until the wealth is
 aggregated in a few hands, and the republic is destroyed."
 - Abraham Lincoln, November 21, 1864



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