Neural signatures of turn-induced freezing of gait in Parkinson’s disease: insights from phase-specific cortico-subthalamic dynamics

Freezing of gait (FOG), particularly during turning, is common in Parkinson's disease (PD), but its phase-specific neural mechanisms remain unclear. This study investigated cortico-subthalamic dynamics underlying turning-induced FOG and their modulation by dopaminergic medication. Local field potentials from primary motor cortex (M1), premotor cortex (PMC), bilateral subthalamic nucleus (STN), and kinematic data were recorded from 19 PD patients during timed up-and-go tasks in medication-off and medication-on states. Turns were segmented into four phases: TurnPre, TurnStart, TurnEnd, and TurnPost. During freezing episodes, alpha power in M1 and PMC significantly decreased in early turning phases. Enhanced PMC-STN coherence appeared during TurnPre in normal turning and TurnStart in freezing turning, with TurnPre alpha suppression and coherence predicting freezing duration. Medication normalized these abnormal oscillations and improved turning. These findings reveal phase-specific cortico-subthalamic disruptions in FOG and suggest novel electrophysiological biomarkers for intervention. Trial Registration: ChiCTR1900026601, registered October 15, 2019.