Functional recovery after serial ablation of prefrontal cortex in the rat

In two experiments, adult rats with 1-stage or 2-stage ablation of discrete subfields of the prefrontal cortex were compared on spatial delayed alternation, one way active avoidance, food hoarding, ingestive behavior, and postoperative body weight. Single stage removal of the ventrolateral (sulcal or orbital) cortex produced aphagia and adipsia for several days postoperatively and a chronic reduction in body weight. Serial removal of this same cortex produced a milder effect on postoperative food and water intake, and there was no chronic reduction of body weight. Ablation of dorsomedial cortex either in one or two stages did not significantly reduce food or water intake or body weight. In contrast, single stage removal of dorsomedial cortex produced dramatic impairment on spatial delayed alternation, active avoidance, and food hoarding; whereas ventrolateral lesions either in one or two stages did not significantly affect performance on these tasks. Animals with dorsomedial lesions produced in two stages were not significantly impaired on delayed alternation or active avoidance, but on food hoarding they were just as impaired as the animals with comparable lesions induced in a single stage. It is apparent that removal of either dorsomedial or ventrolateral prefrontal cortex in two stages causes an amelioration of the deficit that is obtained with single stage destruction of these areas on some tasks, but sparing of function is not an invariant consequence of serial destruction of rat prefrontal cortex.