removing the motor cortex (Lashley)
David at longley.demon.co.uk
Wed Jan 7 21:11:18 EST 1998
In article <68ugv0$1ds at scotsman.ed.ac.uk>
joannab at holyrood.ed.ac.uk "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).
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 http://www.longley.demon.co.uk
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