Perseveration in extinction and in discrimination reversal tasks following selective frontal ablations in Macaca mulatta

BUTTER, C. M. Perseveration in extinction and in discrimination reversal tasks /bllowing selective frontal ablations in Macaca mulatta. PHYSIOL. BEHAV. 4 (2) 163--171, 969.--In order to determine whether the perseverative syndrome exhibited by monkeys with frontal lobe lesions can be fractionated by partial frontal lesions, monkeys with dorsolateral frontal lesions, those with orbital frontal esions, and those with partial orbital esions were tested in three tasks: extinction of a food rewarded bar pressing response, spatial discrimination reversals and object discrimination reversals. Perseveration fbar-pressing in extinction was selectively related to the posteromedial or "limbic " portion of orbital frontal cortex. Deficits in object discrimination reversal, on the other hand, were specifically associated with the lateral sector of orbital cortex and possibly to the adjoining ventral portion of dorsolateral frontal cortex as well. Impairment inspatial discrimination reversal was most severe in monkeys with dorsolateral frontal removal. These findings suggest that the perseverative effects of orbital frontal ablation cart be fractionated into at least two components and further support he view that dorsolateral frontal cortex is associated with spatial factors. Dorsolateral frontal cortex Orbital frontal cortex Object discrimination reversal Rhesus monkey Lesion Extinction Spatial discrimination reversal REMOVAL OF prefrontal cortex in monkeys produces per