Introduction Bradykinesia (i.e., slow movements) is one of the most prominent symptoms of Parkinson's disease (PD) and has a negative impact on quality of life. Rhythmic auditory stimulation (RAS), a widely used and promising treatment technique, has been shown to effectively improve gait speed in PD patients. However, only few studies have explored effects and neural mechanisms of RAS on upper-limb movements. The investigators will conduct two studies to investigate effects and mechanisms of RAS on upper-limb movements in PD patients. The purpose of this study is to examine real-time neural activity when patients with PD and healthy controls listen to RAS and execute finger-tapping task simultaneously.

Methods and analysis This study will recruit patients with PD and healthy controls. Electroencephalography (EEG) will be used under six conditions related to a finger-tapping task. Two-way repeated measures analysis of variance will be performed to investigate the group and condition effects on neural mechanisms.

Study significance This study will offer evidence on RAS effects and mechanisms by investigating the changes in upper-limb movements and neural mechanisms during auditory-motor entrainment. Results from this study will provide a solid foundation for further research and clinical applications of RAS.

Inclusion Criteria:

• (a) idiopathic PD diagnosed by a neurologist based on the Movement Disorders Society clinical diagnostic criteria;
• (b) the Hoehn and Yahr stage is 2 or 3, meaning that bilateral movement problems or combination with mild postural instability;
• (c) a score of Montreal Cognitive Assessment (MoCA) is equal to or higher than 21 to ensure that they understand experimental instructions;
• (d) a score of Edinburgh Handedness Inventory is above 60 to ensure that they are right-handed;
• (e) types and doses of medications remain unchanged in the past month right before participation.
• Age- and sex-matched healthy controls who filled the criteria (c) and (d) will be recruited from communities.

Exclusion Criteria:

• the presence of medical conditions or diseases that may affect hand movements, vision, or hearing based on self-report.

Patients with Parkinson's disease