The present study seeks to examine the efficacy of multi-session transcranial direct current stimulation applied over the primary motor cortex in people with Parkinson's disease on sequential motor learning performance.

Parkinson's disease is characterised by deficits of motor control triggered by impaired basal ganglia function, such as bradykinesia and tremor. Beyond the visibly recognisable motor symptoms of Parkinson's disease, the ability to learn a sequence of movements is also compromised and poses a significant barrier to effective rehabilitation. In healthy individuals, transcranial direct current stimulation applied over the primary motor cortex during motor task practice has been shown to significantly improve motor learning compared to placebo conditions.

The present study seeks to examine the effect of multi-session transcranial direct current stimulation applied over the primary motor cortex in people with Parkinson's disease on sequential motor learning performance. Participants will be required to attend eight laboratory sessions, comprising five intervention and three assessment sessions and will be tested on their ability to learn a 16-digit finger tapping sequence with their right hand. Sessions one to five will form the intervention and will be performed at the same time on consecutive days (i.e. mon-fri). In addition, session one will double as a baseline assessment and intervention session. Assessments sessions will be performed once before the intervention (session one), and three times following the intervention on day three, one week, and four weeks post intervention.

Inclusion Criteria:

• Right-handed (Edinburgh Handedness Inventory; ≥50)
• Cognitively capable (Montreal Cognitive Assessment (MoCA); ≥23)
• Mild to moderate Parkinson's disease severity (Hoehn and Yar disease stage 2-3)
• On stable dopaminergic medication

Exclusion Criteria:

• History of stroke
• Comorbidity
• Cephalic implants