Sensitivity of medial frontal cortex to response and nonresponse conflict.

The anterior cingulate cortex (ACC) holds a prominent place in models of the neural architecture supporting cognitive control and conflict processing. The findings of empirical and computational work lead to the prediction that the ACC is sensitive to response conflict and insensitive to nonresponse conflict. We tested this prediction in two experiments using event-related brain potentials in combination with a task in which some trials included only nonresponse conflict and others included nonresponse and response conflict. A N450 associated with the activity of neural generators in the ACC and anterior frontal region was elicited on trials including only nonresponse and nonresponse and response conflict. This finding is inconsistent with the hypothesis that activation of the ACC is limited to response conflict and may identify one avenue of development in future applications of conflict theory.