Topographic restoration of visual spatial attention in the cortically blind cat

We explored the mechanisms of spatial attention in the cat with a combination of permanent and reversible lesion techniques. Animals with large unilateral visual cortical lesions displayed profound blindness of contralesional visual space. However, cooling deactivation of either posterior parietal cortex or the superior colliculus (SC) in the contralesional half of the brain restored visual orienting responses in the blind hemi4eld. Interestingly, gradual SC deactivation by decreasing cooling loop temperatures produced a topographic restoration of orienting responses, starting at the midline and progressing towards more peripheral eccentricities in the previously blind 4eld. These e6ects can be explained within a computational model for spatial orienting, which represents the interhemispheric competition of bilateral brain structures that possess a topographic, center-magni4ed representation of the external visual space. c © 2002 Published by Elsevier Science B.V.