Cascade of neural processing orchestrates cognitive control in human frontal cortex 1 2

20 Rapid and flexible interpretation of conflicting sensory inputs in the context of current 21 goals is a critical component of cognitive control that is orchestrated by frontal cortex. 22 The relative roles of distinct subregions within frontal cortex are poorly understood. To 23 examine the dynamics underlying cognitive control across frontal regions, we took 24 advantage of the spatiotemporal resolution of intracranial recordings in epilepsy patients 25 while subjects resolved color-word conflict. We observed differential activity preceding 26 the behavioral responses to conflict trials throughout frontal cortex; this activity was 27 correlated with behavioral reaction times. These signals emerged first in anterior 28 cingulate cortex (ACC) before dorsolateral prefrontal cortex (dlPFC), followed by medial 29 frontal cortex (mFC) and then by orbitofrontal cortex (OFC). These results disassociate 30 the frontal subregions based on their dynamics, and suggest a temporal hierarchy for 31 cognitive control in human cortex.