Midfrontal Oscillatory Alterations During Gait Imagination and Observation in Parkinson's Disease with Freezing of Gait

Background. Freezing of gait (FOG) is a debilitating motor symptom of Parkinson's disease (PD) that reflects a breakdown in both motor automaticity and cognitive control. Cognitive strategies, such as motor imagery (gait imagination, GI) and action observation (gait observation, GO) are increasingly used in rehabilitation, yet their neural underpinnings in PD remain unclear. Objectives. To examine midfrontal oscillations during GI and GO in healthy controls (HC), people with PD without FOG (PDFOG –), and with FOG (PDFOG+). Methods. In this study, we used electroencephalography (EEG) to examine midfrontal oscillations during GI and GO in HC (n=21), PDFOG –(n=16), and PDFOG+ (n=21). Resting-state EEG (eyes –closed and eyes –open) served as baselines. Results. Across tasks, both PD groups showed elevated midfrontal theta power relative to HC, while beta oscillations differentiated PDFOG – from PDFOG+. During GO, PDFOG – displayed higher power in both lower and higher frequency bands, whereas PDFOG+ showed reduced alpha and beta power compared to PDFOG –. In GI, PDFOG+ exhibited reduced beta power compared to PDFOG –. Importantly, slowing the pace of GI or GO in PDFOG+ led to reductions in delta, theta, and beta activity, approximating patterns observed in HC. Conclusions. These findings suggest that GI and GO recruit overlapping but partially distinct control mechanisms, with impaired oscillatory engagement in PDFOG+. Slowing task pace appears to normalize midfrontal rhythms, potentially by reducing cognitive-motor demands. These oscillatory signatures provide mechanistic insight into gait-related dysfunction and supports the refinement of motor imagery and action observation as targeted rehabilitation strategies for PD.