Background: Freezing of gait (FoG) is a debilitating symptom for patients with Parkinson's disease (PD). FoG not only impairs walking but also significantly increase fall risks and decrease quality of life for patients with PD. Despite the critical consequences, the mechanisms associated with this phenomenon are not well understood.~Clinically, FoG often occurs when individuals with PD are approaching a narrow pathway or crossing a busy street. This observation leads to the hypothesis that FoG is associated with context-dependent motor performance, a phenomenon that an individual demonstrate poorer performance if the learned motor task is carried out in an unfamiliar context. Whether the occurrence of freezing episodes is a result of context-dependency has not been systematically investigated. Moreover, the changes in corticomotor excitability associated with FoG have not been well-established.~Objectives: The objectives of this proposal are to understand the behavioral and neurophysiological mechanisms of FoG. The specific aim is to examine the behavioral changes in context-dependency and changes in corticomotor excitability associated with FoG.~Methods: a total of 70 participants, including PD patients with FoG, PD patients without FoG, and age-matched non-disabled adults, will be recruited. The participants will undergo behavioral and neurophysiological examinations. Behavioral evaluations will include context-dependent motor performance, FoG, disease severity, and walking and balance functions. Transcranial magnetic stimulation and electroencephalogram will be used to measure corticomotor excitability of the participants. Analysis of variance (ANOVA) and regression analysis will be performed to compare and determine the relationship between FoG, behavioral outcomes, and corticomotor excitability. Statistical significance level is set at p < 0.05.
The overall goals of this proposed study are to investigate the behavioral and neurophysiological mechanisms of patients with Parkinson's disease (PD) experiencing freezing of gait (FoG). More specifically, we aim to determine the behavioral changes in context-dependency and changes in corticomotor excitability associated with FoG.