Background: Stimulation of alpha-2 adrenoceptors in the monkey or rat prefrontal cortex (PFC) has been known to improve spatial working memory (SWM) and stimulation of alpha-1 adrenoceptors in the rat PFC has been reported to impair SWM. The present study attempted to replicate in monkey the rat experiments on alpha-1 adrenoceptor stimulation.
Methods: The alpha-1 adrenergic agonist phenylephrine or the alpha-2 adrenergic agonist guanfacine was infused into the dorsolateral prefrontal cortex (dlPFC) of monkeys performing the delayed-response (DR) task, a task of SWM, to see how the drugs affect SWM performance.
Results: Phenylephrine infusion in dlPFC significantly impaired DR performance, whereas guanfacine improved performance. The effects of both drugs were delay-dependent. Infusions outside dlPFC were ineffective.
Conclusions: Stimulation of prefrontal cortical alpha-1 adrenoceptors impairs SWM function in monkeys, consistent with the parallel study in rats, whereas stimulation of alpha-2 adrenoceptors improves SWM, indicating that alpha-1 and alpha-2 adrenoceptors may have opposing roles in the PFC.