I recently read on p. 6051 of
A.K. Engel & al.: Proc. Natl. Acad. Sci. USA, Vol. 88, pp. 6048-6052, July
1991.
that that neuronal responsiveness and receptive field properties in the
visual area PMLS (posteromedial lateral suprasylivian sulcus), a visual
area dealing with motion and global shape, are essentially unchanged after
ablation of the primary visual area. They quoted as reference:
P.D. Spear & T.P. Baumann: J. Neurophysiol., Vol. 42, pp. 31-56, 1979.
R. Guedes & al.: Exp. Brain Res., Vol. 49, pp. 13-27, 1983.
I do not have the latter two papers, and cannot comment on their contents.
Now I always thought that visual information from the retina goes first to
LGN, then to the primary visual area V1, from which axons make synapses
with other visual areas. Thus destruction of the primary visual area leads
to cortical blindness. There seems to be a contradiction.
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?
If someone has read these two papers, (s)he can enlight me.
I already asked the question in the cognitive neuroscience mailing list
(cogneuro at ptolemy.arc.nasa.gov), but got no satisfactory answer.
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Christian Ronse ronse at dpt-info.u-strasbg.fr
Universite Louis Pasteur
Departement d'Informatique
7 rue Rene Descartes Tel. (33) 88.41.66.38
F-67000 Strasbourg Fax. (33) 88.61.90.69
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