removing the motor cortex (Lashley)

Joanna Bryson joannab at holyrood.ed.ac.uk
Tue Jan 6 19:06:56 EST 1998


A question from someone outside the field --

I was reading in Lashley (in search of the engram, 1950) where he
removed the entire motor cortex from monkeys who had learned complex
motor tasks (opening different forms of latched box.)  The animals
were paralyzed for 8-12 weeks, but on recovery (without having been
exposed to the boxes since their operation) they were able to open
the boxes completely fluently.

Lashley concluded that the motor cortex had nothing to do with 
voluntary movement nor learning of "reflexes" / skills.  It seems
more likely that during the 8-12 weeks, another part of the cortex is
being converted into a new motor cortex, and the knowledge embedded in
the undamaged parts of the motor "loop" are sufficient to constrain
the "new" motor cortex into completing the established patterns, whether
routine skills or these esoteric ones.  

Er... could someone catch me up on current theory with regard to 
this kind of recovery?  Am I on target?  I know there's lots of work
with remapping sensory and motor cortecies when parts of the animal's
body changes, and also on language moving around when the brain is
damaged, but I hadn't heard of something quite on this scale before.
I'd be just as interested in simulated models of this (I do AI).


Thanks,

Joanna




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