Disinhibition after prefrontal lesions as a function of duration of intertrial intervals

Dogs were trained preoperatively in both positive and inhibitory conditioned food reflexes on a schedule of either a 15-second or 1-minute intertrial interval. After lesions had been made in the medial surface of the prefrontal cortex, errors of disinhibition occurred in both schedules and in association with an increased "drive" for food. In contrast, lesions of the dorsolateral prefrontal cortex produced the disinhibition syndrome only in the group which was tested at short intertrial intervals, and no increase in food-directed activity was noticed. In each instance the postoperative recovery was very rapid. It is suggested that the quality of disinhibition in prefrontal animals is different, depending on the placement of the lesion.