Right Ventrolateral Prefrontal Cortex Mediates Individual Differences in Conflict-driven Cognitive Control

摘要

Conflict adaptation—a conflict-triggered improvement in thenresolution of conflicting stimulus or response representations—nhas become a widely used probe of cognitive control processesnin both healthy and clinical populations. Previous fMRI studiesnhave localized activation foci associated with conflict resolutionnto dorsolateral PFC (dlPFC). The traditional group analysis approachnemployed in these studies highlights regions that are,non average, activated during conflict resolution, but does not necessarilynreveal areas mediating individual differences in conflictnresolution, because between-subject variance is treated as noise.nHere, we employed a complementary approach to elucidate thenneural bases of variability in the proficiency of conflict-drivenncognitive control. We analyzed two independent fMRI data setsnof face–word Stroop tasks by using individual variability in thenbehavioral expression of conflict adaptation as the metric againstnwhich brain activation was regressed while controlling for individualndifferences in mean RT and Stroop interference. Acrossnthe two experiments, a replicable neural substrate of individualnvariation in conflict adaptation was found in ventrolateral PFCn(vlPFC), specifically, in the right inferior frontal gyrus, pars orbitalisn(BA 47). Unbiased regression estimates showed that variabilitynin activity in this region accounted for ∼40% of the variance innbehavioral expression of conflict adaptation across subjects, thusndocumenting a heretofore unsuspected key role for vlPFC innmediating conflict-driven adjustments in cognitive control. Wenspeculate that vlPFC plays a primary role in conflict control thatnis supplemented by dlPFC recruitment under conditions of suboptimalnperformance.