How the prefrontal cortex and subthalamic nucleus coordinate their activity during decision-making

How do the medial prefrontal cortex (mPFC) and the subthalamic nucleus (STN) coordinate their activity to support cognitive control? Specifically, the authors investigated how these two structures interact during conflict, response inhibition, and trial-to-trial behavioral adjustments.

The researchers performed simultaneous intracranial recordings from the mPFC and the STN in 22 patients undergoing deep brain stimulation (DBS) surgery for Parkinson's disease. Participants performed a novel response inhibition task involving Go trials (simple movement), Conflict trials (requiring movement in the opposite direction), and NoGo trials (requiring complete response inhibition). The team analyzed local field potential (LFP) power and phase coherence in the theta (2–5 Hz) and beta (8–30 Hz) frequency bands, alongside multi-unit spiking activity.

The study reveals a functional segregation between the two regions based on the timing and frequency of oscillations. Within a trial, increased theta phase synchrony between the mPFC and STN signals conflict and the need for inhibition. However, the regions play different roles: mPFC theta power is associated with response inhibition, while STN theta power is linked to movement execution.

Across trials, beta oscillations serve as the primary mechanism for adaptation. Post-response increases in mPFC beta power reflect the difficulty of the completed trial. Subsequently, elevated STN beta power at the start of the next trial correlates with slower response times, suggesting that the STN implements the behavioral adjustments initiated by the mPFC. The authors conclude that the behavioral significance of oscillatory activity is determined by the specific circuit in which it is expressed, rather than the frequency band alone.

This research clarifies the hierarchical and complementary relationship between cortical and subcortical structures during cognitive control. By demonstrating that the mPFC and STN are not merely redundant but perform distinct, sequenced stages of decision-making, the study provides a framework for understanding how network-level disruptions—such as those seen in Parkinson's disease—can impair executive function.