Neural dynamics of proactive and reactive cognitive control in medial and lateral prefrontal cortex.

Goal-directed behavior requires adjusting cognitive control, both in preparation for and in reaction to conflict. Theta oscillations and population activity in dorsomedial prefrontal cortex (dmPFC) and dorsolateral PFC (dlPFC) are known to support reactive control. Here, we investigated their role in proactive control using human intracranial electroencephalogram (EEG) recordings during a Stroop task that manipulated conflict expectations. During response selection, conflict processing enhanced dlPFC beta desynchronization, dmPFC theta increases, and high-frequency activity (HFA, which indexes local population activity) in both regions. After responses, conflict suppressed theta and boosted beta rebounds in both regions. Importantly, pre-trial dmPFC theta increased when conflict was anticipated, and within-trial theta, beta, and HFA dynamics were accentuated when conflict was rare. These findings reveal how the balance of reactive and proactive control modulates shared HFA and dissociable theta-beta conflict signals in dmPFC and dlPFC and identifies pre-trial dmPFC theta as a candidate substrate for proactive control.