Parkinson's Disease| Part A (SAD): BIIB094 Dose 1

Inclusion Criteria:

• Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use confidential health information in accordance with national and local participant privacy regulations.
• Diagnosed with PD within 7 years at the time of initial enrollment (i.e., at time of SAD enrollment for rollover participants), without major motor fluctuations or dyskinesia that may interfere with study treatment and assessments in the opinion of the investigator after consultation with the Sponsor.
• Modified Hoehn and Yahr Stage ≤ 3.

Exclusion Criteria:

• Montreal Cognitive Assessment (MoCA) score less than (
• History of any brain surgery for PD or a history of focused ultrasound treatment at any time; or history of neuromodulation procedures.
• Transient ischemic attack or stroke or any unexplained loss of consciousness within 1 year before Screening.
• History of unstable angina, myocardial infarction, chronic heart failure, or clinically significant conduction abnormalities within 1 year before Screening.
• Poorly controlled diabetes mellitus, as defined by having dosage adjustment of diabetic medication within 3 months before dosing (Day 1) or glycosylated hemoglobin value greater than or equal to (≥) 8 percent (%) at Screening.
• History or positive test result at Screening for human immunodeficiency virus.
• History or positive test result at Screening for hepatitis C virus antibody.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.