DISSOCIABLE EFFECTS OF CINGULATE AND MEDIAL FRONTAL-CORTEX LESIONS ONSTIMULUS-REWARD LEARNING USING A NOVEL PAVLOVIAN AUTOSHAPING PROCEDURE FOR THE RAT - IMPLICATIONS FOR THE NEUROBIOLOGY OF EMOTION

The effects of quinolinic acid-induced lesions of the anterior cingula te, posterior cingulate, and medial frontal cortices on stimulus-rewar d learning were investigated with a novel Pavlovian autoshaping proced ure in an apparatus allowing the automated presentation of computer-gr aphic stimuli to rats (T. J. Bussey, J. L. Muir, & T. W. Robbins, 1994 ). White vertical rectangles mere presented on the left or the right o f a computer screen. One of these conditioned stimuli (the CS+) was al ways followed by the presentation of a sucrose pellet; the other, the CS-, was never followed by reward. With training, rats came to approac h the CS+ more often than the CS-. Anterior cingulate cortex-lesioned rats failed to demonstrate normal discriminated approach, making signi ficantly more approaches to the CS-than did sham-operated controls. Me dial frontal cortex-lesioned rats acquired the task normally but had l onger overall approach latencies. Posterior cingulate cortex lesions d id not affect acquisition.