Performance monitoring by the supplementary eye field

Intelligent behaviour requires self-control based on the consequences of ac tions. The countermanding task is designed to study self-control; it requir es subjects to withhold planned movements in response to an imperative stop signal, which they can do with varying success. In humans, the medial fron tal cortex has been implicated in the supervisory control of action(1-3). I n monkeys, the supplementary eye field in the dorsomedial frontal cortex is involved in producing eye movements, but its precise function has not been clarified(4). To investigate the role of the supplementary eye field in th e control of eye movements, we recorded neural activity in macaque monkeys trained to perform an eye movement countermanding task. Distinct groups of neurons were active after errors, after successful withholding of a partial ly prepared movement, or in association with reinforcement. These three for ms of activation could not be explained by sensory or motor factors. Our re sults lead us to put forward the hypothesis that the supplementary eye fiel d contributes to monitoring the context and consequences of eye movements.