Distinct roles for the anterior cingulate and dorsolateral prefrontal cortices during conflict between abstract rules

Distinct patterns of activity within the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC) reported in neuroimaging studies during tasks involving conflict between competing responses have often been cited as evidence for their key contributions to conflict-monitoring and behavioural-adaptation, respectively. However, supporting evidence from neuropsychological patients has been scarce and contradictory. We administered a well-studied analogue of the Wisconsin Card Sorting Test (WCST), designed to elicit conflict between two abstract rules, to a cohort of six patients with damage to ACC or dlPFC. Patients who had sustained more significant damage to the ACC were not impaired either on a measure of conflict cost nor on measures of conflict-induced behavioral adaptation. In contrast, damage to dlPFC did not affect the conflict cost measure but abolished the patients’ ability to adapt their behavior following exposure to conflict, compared to controls. This pattern of results complements the findings from non-human primates with more circumscribed lesions to ACC or dlPFC on the same task and provides converging evidence that ACC is not necessary for performance when conflict is elicited between two abstract rules, whereas dlPFC plays a fundamental role in behavioral adaptation