IUBio

PMLS reponse without V1

Anthony R McIntosh mcintosh at rocky.nia.nih.gov
Mon Sep 27 21:18:51 EST 1993


In article <1993Sep27.155032.12568 at gserv1.dl.ac.uk> ronse at fr.u-strasbg.dpt-info writes:
>  ..... paper concerning responses in suprasylvian cortex after
>  inactivation of primary visual cortex
>
>
>Is there an explanation in terms of information carried by the tectofugal
>system (another route which goes through the superior colliculus to
>visuo-motor areas)? It is known that patients with cortical blindness
>(destroyed V1) can "guess" the position of a visual stimulus thanks to this
>system, which allows them to automatically move their eyes towards the
>stimulus. Any other explanation?

I think you probably answered your question pretty satisfactorily all
ready, but to elaborate, the tectal system is an anatomically and
physiologically rich area so it's quite likely that the responses in
lateral suprasylvian are related to the tectum.  Moreover, projections
from the pulvinar/lateral posterior n. (which in turn receives input
from the colliculi) terminate in secondary visual cortices as well as
asssociation regions like area 36.  The LPN also may receive direct
retinal input which makes life even more complicated.  The results may
also be explain by projections of the LGN to non-V1 sites, but that
depends on the size of the lesion that was made.  The LGN sends
projections to area 18 and perhaps 19 depending on who you ask.

Randy



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