Brain study aims to unlock mystery of sudden freezing in Parkinson's

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Diagnosis of idiopathic PD. * Age 21-75 (see Inclusion of Individuals across the Lifespan for justification of age range). * Able to ambulate independently without the use of an assistive device (e.g. cane) for 50 meters. * Implanted Medtronic Percept TM Device. * At least 3 months since the initial activation of the neurostimulator. * Undervalued, under-represented, or disenfranchised social group may be included. * Active members of the military (service members), DoD personnel (including civilian employees) may be included. * Individual or group that is disadvantaged in the distribution of social goods and services such as income, housing, or healthcare may be included. Exclusion Criteria: * Meet criteria for dementia with Lewy bodies, Multiple Systems Atrophy, Alzheimer's disease, or other neurodegenerative disorder. * History of seizures or other significant neurological disorders that may affect participation or performance in the study. * History of musculoskeletal disorders that significantly affect walking or movement of limb(s) that would affect the participation in the experimental task (Participants will be excluded from that task, but may participate in other tasks, for example, may be excluded from Experiment 1 if the disorder affects walking, but may still participate in Experiment 3). * History of muscular conditions of the neck and back, including whiplash that would affect walking experiments. * History of visual and/or vestibular conditions that may affect participation or performance in the study. * Reduced capacity to consent. This will be assessed using a 2-stage process. Initially, participants will be tested using the University of California, San Diego, Brief Assessment of Capacity to Consent (UBACC). If concerns are raised from the UBACC test, the individual will be further tested using the MacArthur Competency Assessment Tool. * Pregnant people. * Post-operative complications or adverse effects (e.g. ON stimulation dystonia) that affect patient safety or confound the experiment.