抄録
To adapt behavior to changing environment, one must monitor outcomes of executed actions and adjust subsequent actions accordingly. However, little is known about neural processes underlining this link from performance monitoring to performance adjustment. To reveal neural mechanisms of the link, we trained two monkeys in a task that required frequent learning of action based on visual feedback stimuli. While the monkey was performing the task, we recorded the activity of single cells from the medial and lateral prefrontal cortex (PFC). About one-fourth of cells in both medial and lateral PFC responded to the feedback stimuli. However, the proportion of cells that differentially responded to positive and negative feedback stimuli was significantly larger in the medial PFC than in the lateral PFC (p<0.05). The visual features or novelty of the stimuli, or stay/shift for the next action did not account for the selectivity of responses, and therefore the responses represented evaluation of the executed action. Moreover, the response to the positive-feedback stimuli decreased along the course of action learning, in proportion to the amount of prediction error of action value calculated based on the behavior. Therefore, we suggest that the medial PFC cells signal the direction and amount of errors in the predicted value of executed action to specify the adjustment for subsequent action selection. [J Physiol Sci. 2007;57 Suppl:S25]
