Abstract
Small, unilateral cortical lesions were placed in either medial-anterior, lateral-anterior, or posterior cortex of 20 male, Sprague-Dawley, albino rats. In addition, unilateral sham operations were performed on 8 rats from the same stock. All subjects had been trained prior to surgery with diametrically opposed visual habits mediated by opposite cerebral hemispheres. The opposing habits were, insofar as possible, evenly matched prior to surgery. After surgery, lesioned hemispheres, regardless of locus of lesion, were slower in acquiring the habit they mediated, than were unlesioned hemispheres. Further, unlesioned hemispheres dominated in test trials in which subjects chose one of the two cue doors with both eyes open. These findings confirm that the “interocularly conflicting discrimination” baseline detects a role of extrastriate cortex in mediation of pattern discrimination habits. They further indicated that losses occur without regard to the various locations of lesion employed.
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