The Roles Of The Monkey Prefrontal Cortex In Inhibitory Control Of Behavior And Counting Performance

Human and animals have a fundamental ability to suppress inappropriate actions, a cognitive function termed inhibitory control of behavior. Extensive studies indicate that the prefrontal cortex (PFC) plays a key role in this function. However, its neural mechanism is unclear.Non-human primates possess a biologically determined representation of numerosity. It is documented that they have a capability to subitize small numerousness and judge relative numerousness. However, it is not clear whether they have a counting ability, one of the most important numerical competences, and whether PFC, the highest functional association area, is involved in counting performance.Part 1: Selective deficit in no-go performance induced by blockade of prefrontal cortical a2-adrenoceptors in monkeysIt is demonstrated that a2-adrenoceptors (012-ARs) in the dorsolateral PFC (dIPFC) play a key role in working memory. In order to determine if 012-ARs are involved in PFC neural mechanism underlying inhibitory control of behavior, we investigated the effect of chronic infusion of the a.2-adrenergic antagonist yohimbine into the dIPFC on a visually guided go/no-go task. The no-go but not go performance was selectively impaired during administration of yohimbine: the monkeys showed an inability to inhibit the touching response to the no-go signal. Similar infusion of saline had no effect. The present studyprovides direct behavioral pharmacological evidence that a2-ARs in the dIPFC are involved in response inhibition.