[The anterior cingulate cortex in error detection and conflict monitoring. Unitary neuronal activity in monkeys].

Using a Stroop-like visuo-motor task in monkeys, we studied the unitary neuronal activity of the anterior cingulate cortex (ACC, CMAr : 24c) during error detection and conflict monitoring. A high percentage of cingular neurons modified their firing frequency during both attentional and evaluation periods. During the latter period, however, changes in discharge rates were always much more pronounced for erroneous responses than for successful movements that induced reward delivery. Moreover, some neurons responded more markedly to the warning stimulus when a previous trial failed In this case, the probability of a subsequent correct response increased. Such a neuronal apparatus could represent an error compensation system that serves to adapt a subject's behavioral response following an unfavorable and unexpected outcome. Abnormal activity of these neurons, which appear to take advantage of past errors, could contribute to the genesis of obsessive-compulsive disorders (OCD).