Investigating the Neural Signature of Freezing of Gait in Parkinson's Disease

Inclusion Criteria: 1. Clinical diagnosis of Parkinson's disease (PD) made by a Neurologist\* 2. Modified Hoehn \& Yahr (H\&Y) Stage I to IV in the ON medication state 3. Age above 18 years\* 4. Able to walk 5 minutes while unassisted by a walker or another person (the use of a cane is allowed).\* 5. Mini Mental State Examination\>= 21 6. At least three hours in-between regular medication intakes to allow for stable testing time.\* 7. Self-reported FOG with a severity of at least 1 FOG episode per day, based on items 1 and 2 of the New Freezing of Gait Questionnaire, irrespective of FOG occurring ON- or OFF-medication.\* 8. Stable medication scheme for at least 7 days before enrollment. Exclusion Criteria: 1. Participation in another clinical intervention study\* 2. Acute musculoskeletal or other neurological, psychiatric, or cardiovascular conditions affecting gait or any other medical condition which, in the opinion of the investigator, may prevent the participant from completing the protocol in full 3. Unable to adhere to assessment procedures leading to missing or unusable data, as determined by the investigators 4. Not a stable medication scheme for at least 7 days before the assessment.\* 5. Occurrence of any of the following within 3 months prior to informed consent: * Orthopedic surgery of the lower extremity * Myocardial infarction * Hospitalization for unstable angina * Coronary artery bypass graft * Percutaneous coronary intervention * Implantation of a cardiac resynchronization therapy device * Implantation of deep brain stimulation 6. Substance abuse that may interfere with the patient's compliance