Reason for crossed projections in the nervous system?
rubinsnk at is2.nyu.edu
Thu Nov 16 17:18:12 EST 1995
Matt Jones (jonesmat at ohsu.edu) wrote:
: Here's one hypothesis I heard in an undergraduate class. I have no idea
: whether there's any evidence.
: 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).
That seems derived from Coghill's thesis in 'Anatomy and the Problem of
Behavior' (1929). He posited the need for crossed connections in a
multicelled pre-vertebrate to convey chemical or tactile stimuli to
contralateral effectors for avoidance. From this, he builds a model of
spinal cord organization.
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