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Cameron S. Carter,* Todd S. Braver, Deanna M. Barch, Matthew M. Botvinick, Douglas Noll, Jonathan D. Cohen
An unresolved question in neuroscience and psychology is how the brain monitors performance to regulate behavior. It has been proposed that the anterior cingulate cortex (ACC), on the medial surface of the frontal lobe, contributes to performance monitoring by detecting errors. In this study, event-related functional magnetic resonance imaging was used to examine ACC function. Results confirm that this region shows activity during erroneous responses. However, activity was also observed in the same region during correct responses under conditions of increased response competition. This suggests that the ACC detects conditions under which errors are likely to occur rather than errors themselves.
It has been proposed that the ACC plays a prominent role in the executive control of cognition (1). This hypothesis is based, in part, on functional neuroimaging studies that show ACC activity during tasks that engage selective attention, working memory, language generation, and controlled information processing (2). Disturbances in this brain region have been reported in disorders associated with cognitive impairment, including schizophrenia and depression (3). This account of ACC function is consistent with the rich anatomical connectivity of this region with association, limbic, and motor cortices (4). However, it is lacking in detail regarding the precise contribution of the ACC to cognitive control.
To date, the most explicit hypothesis regarding ACC function comes from event-related brain potential (ERP) studies during speeded response tasks. These studies have reported an error-related negativity (ERN), peaking 100 to 150 ms after a person shows electromyographic evidence of initiating an incorrect response. Dipole modeling suggests that the ERIQ has a medial frontal generator, possibly the ACC (5). These and other characteristics of the ERN have led to the hypothesis that the ACC is involved in monitoring and compensating for errors. Specifically it has been proposed that this involves a comparator process in which a representation of the intended, correct response is compared to a representation of the actual response (5, 6).
We propose that rather than implementing a comparator process, the ACC monitors competition between processes that conflict during task performance. For example, response competition arises when a task elicits a prepotent but inappropriate response tendency (manifested as activity in...