left-right reversal of CNS: Why?

kenneth paul collins KPCollins at postoffice.worldnet.att.net
Wed Sep 11 21:02:27 EST 1996


>Further, there are a number of motor and sensory
>and motor homunculi, in thalamus and basal ganglia, and in cerebellum,
>and I'm not sure that "upside down" describes them especially well;

They're all in "perfect" register... for instance, ipsilateral primary 
sensory & motor maps are "face-to-face" mirror images of each other... 
the secondary sensory & motor areas "recapitulate" this mapping but have 
somewhat less-well-defined topographical maps...

...so what is all of this for...?

...this particular mapping is involved in many powerful 
information-processing dynamics... for instance, this particular  
mirror-image mapping forms the substrate for the inverse directionality 
of "fight" and "flight" responses... and at a higher-"level" of detail, 
this same mapping enters profoundly into all "learning"... you see, when 
one experiences anything, a sequential representation of what's 
experienced occurs in sensory cortical areas... such sensory dynamics 
drive "learning"... the production of microscopic trophic modifications 
to the neural circuitry which encode the activation that has actually 
occurred... subsequently, when an analogous motor "program" needs to be 
developed, the formerly-learned sensory memory is accessed (I can 
describe the "addressing" inherent in such) and used as a template to 
guide the convergence of the motor dynamics... can you see it...? the 
advantage that the sensori-motor "face-to-face" mirror-image mapping 
implements is that the =acted-upon= sensory experience is transformed in 
a straight-forward fashion to =act-upon= motor activation... there's a 
bit of sadness involved here, however... these very dynamics enter 
=strongly= into the dynamics of the viscious cycle of Child abuse... the 
Child that is battered (acted-upon-directionality sensory templates) 
becomes the act-upon motor version of those sensory templates acquired 
at the hands of abusive adults... the directionality inherent in the 
be-struck sensory template is inverted, automatically becoming the 
directionality inherent in "striking" behavior... this all happens 
because the nervous system preserves this mapping paradigm with respect 
to the =whole body= ...and because of this, the CNS is able to "know" 
how to activate the musculature, and to do so, via simple TD E/I 
minimization...

...I understand that what's here is not enough, but what's here stands 
verified... ken collins



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