removing the motor cortex (Lashley)

David Longley David at
Wed Jan 7 21:11:18 EST 1998

In article <68ugv0$1ds at>
           joannab at "Joanna Bryson" writes:

> 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
In  the  early  80s,  I was working  on  Noradrenaline  of  Locus 
Coeruleus  origin and reinforcement. After a couple of  years  of 
work  and a lot of theoretical anguish over alternative views  to 
my  supervisor's (T.J. Crow) - such as Steve Mason's - I  finally 
came  to the conclusion that Crow and Kety were probably  was  of 
the  mark.  I  mentioned  Oakley's  work  which  seems  to   have 
demonstrated learning in decorticate rabbits, and then there  was 
Patterson's  work  on  spinal animals. Logically,  this  made  me 
question "cortical" bases for reinforcement, but it also made  me 
look  at hierarchical re-representation of function as  suggested 
way back in the 1890s by Hughlings-Jackson.

In the final analysis our behavioural and psychological  concepts 
are  all  rather dubious. See FRAG.HTM for some of  the  thinking 
this has led to over the years...
David Longley (check end reply line #)

Longley Consulting                                                  London, UK
Behaviour Assessment & Profiling Technology,
Research, Data Analysis and Training Services,
Small IT Systems                      

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