Cortical involvement in a gait-related imagery task: comparison between Parkinson's disease and normal aging.

Purpose: We employed imaginary tasks to investigate the neurophysiology of gait in patients with Parkinson's disease (PD) using functional magnetic resonance imaging (fMRI).

Methods: Cortical activation of gait-related imagery was explored in 13 PD patients, 13 age-matched controls (Old), and 14 young volunteers (Young) using fMRI. The tasks included gait initiation, stepping over an obstacle and gait termination using an event-related design. Subjects watched a video clip showing an actor walking and imagined the walking process.

Results: At gait initiation, no significant difference could be found between PD and the Old controls. Activation in the visual related areas in the Old subjects was increased compared to the Young subjects. While imagining stepping over obstacles, the right dorsal premotor area (PMd), precentral, right inferior parietal lobule, and bilateral precuneus were more activated in PD compared to the Old. An extensive network of bilateral SMA, PMd, posterior parietal lobe and visual association areas was activated in the Old versus the Young subjects. At gait termination, visual related areas were noted when PD was compared to the Old. In contrast, increased activation in bilateral pre-SMA, PMd, ventral premotor area, precentral, posterior parietal lobes and visual association areas were activated in the Old when compared to the Young.

Conclusions: Our study provides image based evidence for gait disturbance in PD patients and during normal aging. The compensatory cortical mechanism in the findings could be a background resource for further therapeutic interventions.