retrograde/anterograde labeling??

kkollins at pop3.concentric.net kkollins at pop3.concentric.net
Fri Nov 27 23:43:48 EST 1998



Ben Godde wrote:

> > All this said, I'll be able to do more with your Q if you answer my queries,
> > above. Cheers, ken collins
>
> ok, I will try again:
>
> Is the occurence of new labelling patterns (labelling based on
> retrograde or anterograde axonal transport) after plastic cortical
> reorganization a proof of the emergence or sprouting of axons.
>
> This questions referes to the work of S Florence and J Kaas (Science,
> this month), showing abnormal labelling patterns in arm amputated
> monkeys, revealing new (functional OR anatomical OR both ??)
> intracortical connections over several millimeters.

I'll get the ref and then comment further... to guard against the possibility that
I've been talking "apples" when you asked, "What about 'oranges'" :-)

> The question is not:
> Is there plasticity (activity dependent or learning induced) in the
> cortex. That is a fact.
>
> and the question is not:
> Is sprouting possible in the neocortex and is it involved in plastic
> processes. I think so.
>
> But the question is:
> Is the author's method able to give last evidence, THE FINAL PROOF, that
> sprouting in the neocortex occurs over several millimeters
> AND
> that the found new connections are NOT due to functional alterations.
>
> Hope, my intention becomes clearer , now.

How could there be new functionality (the "newness" is implicit in the
"altered-ness") without correlated anatomical changes?

In the case of the severed limbs, the "recovering" of the cortical space that's
made available when its inputs are massively-lesioned is old stuff that was
well-documented long ago.

Such "recovering" of newly-available cortical space procedes via simple TD
E/I-minimization, just like everything else within the nervous system does.

I'll see if the article's stuff can help us get "in-sync". ken collins




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