DELAYED-RESPONSE DEFICIT INDUCED BY LOCAL INJECTION OF THE ALPHA(2)-ADRENERGIC ANTAGONIST YOHIMBINE INTO THE DORSOLATERAL PREFRONTAL CORTEXIN YOUNG-ADULT MONKEYS

Two young adult monkeys (Macaca mullata) were trained to perform a del ayed-response task that required the monkeys to remember a cued spatia l position (left or right) over a delay interval and then to make a re sponse to the cued position. Local injection of the alpha(2)-adrenergi c antagonist yohimbine (10 mu g in 2 mu l saline) into the dorsolatera l prefrontal cortex (Walker's area 46 and area 9) impaired the perform ance of the delayed-response task, and it was without effect on the pe rformance of the task if there was no delay between the cue and choice signals. The main performing error after injection of yohimbine was t hat the monkeys responded to uncued position with higher rate. Local i njection of the alpha(1)-adrenergic antagonist prazosin (10 mu g in 2 mu l saline) or the beta beta-adrenergic antagonist propranolol (10 mu g in 2 mu l saline) into the same cortical areas induced no significa nt effect on the performance of the task. The present study suggests t hat prefrontal alpha(2)-adrenoceptors play an important role in the sp atial working memory in young adult monkeys. (C) 1994 Academic Press, Inc.