Midfrontal oscillatory alterations during gait imagination and observation in Parkinson's disease with freezing of gait.

Freezing of gait (FOG) is a disabling motor symptom in Parkinson's disease (PD), linked to impaired motor automaticity and cognitive control. Cognitive strategies like motor imagery (gait imagination, GI) and action observation (gait observation, GO) are used in rehabilitation, but their neural mechanisms are not well understood. This study used EEG to examine midfrontal oscillations during GI and GO in healthy controls (HC, n = 21), PD without FOG (PDFOG-, n = 16), and PD with FOG (PDFOG+, n = 34), with resting-state EEG (eyes-closed and eyes-open) as baseline. During GI, both PD groups showed increased midfrontal theta power compared to HC, while during GO this increase appeared only in PDFOG - . Differences in midfrontal beta oscillations distinguished the two PD subgroups across all conditions. Specifically, the PDFOG - group displayed higher power across alpha and beta frequency bands during GO compared to both HC and PDFOG + . In the GI task, PDFOG + was characterized by significantly reduced beta power compared to the PDFOG - group. Slowing the pace of GI in PDFOG + led to a significant reduction in delta activity, while slowing the pace of GO resulted in significant reductions in both delta and theta power; these frequency-shifts were descriptively closer to oscillatory patterns observed in healthy controls. These findings suggest GI and GO involve overlapping but distinct neural mechanisms. Slower pacing may reduce cognitive-motor load and promote compensatory midfrontal activity. Identifying these oscillatory patterns improves understanding of gait dysfunction and supports refining GI and GO as targeted rehabilitation strategies for people with PD and FOG.