In article <47lg75$h6v at fremont.ohsu.edu> Matt Jones <jonesmat at ohsu.edu> writes:
>From: Matt Jones <jonesmat at ohsu.edu>
>Subject: Re: Reason for crossed projections in the nervous system?
>Date: 6 Nov 1995 17:21:41 GMT
>In article <rambis.815616371 at isum1.iastate.edu> Paul L Pearson,
>rambis at iastate.edu writes:
>>Can anyone give me a solid hypothesis for why the left side of the body
>>is controlled by the right side of the brain and vice versa? This
>Early swimming animals evolved crossed projections from the visual system
>to the motor systems, so that an object perceived on one side of the body
>would cause contraction of the muscles on the opposite side, leading to a
>swimming movement away from the object (escape).
Cajal thought it was to compensate for optical inversion of the images
projected onto the retinas. See "Recollections of my Life" pp. 470-475.
John A. Kiernan
Department of Anatomy
Univ. of Western Ontario
LONDON, Canada N6A 5C1
e-mail: kiernan at uwo.ca
