Lateral frontopolar theta-band activity supports flexible switching between emotion regulation strategies.

Flexible emotion regulation is essential for mental health and well-being. However, neurocognitive mechanisms supporting emotion regulation flexibility remain unclear. Lateral frontal pole (FPl) contributes to flexible behavior by monitoring the efficacy of alternative strategies. This preregistered study examines if FPl also supports flexible use of emotion regulation strategies. It focuses on pre-decision theta-band activity as a potential indicator of this adaptive process. Sixty-three participants performed an emotion regulation strategy-switching task, involving three phases: (1) implementing an instructed (reappraisal or distraction) strategy, (2) deciding whether to 'maintain' the current or 'switch' to the alternative strategy, and (3) implementing the chosen strategy. Results showed that switching is predicted by the reduced efficacy of an initial emotion regulation strategy (indexed with EMG corrugator activity) and is made in accordance with situational demands (stimulus reappraisal affordances). Critically, switching to an alternative emotion regulation strategy is associated with increased theta-band power in FPl around the time of the decision. These findings support the previously established role of FPl theta-band activity in monitoring counterfactual efficacy of alternative strategies. Crucially, they extend this notion to cognitive emotion regulation, thereby offering promising neural targets for stimulation-based therapies aimed at enhancing emotion regulation flexibility in affective psychopathologies.