RecruitingDevice studyApathy in Parkinson Disease TMS StudyThe goal of this clinical trial is to develop non-invasive brain stimulation targets for the treatment of apathy, or motivation problems, in Parkinson Disease. The main questions the study aims to answer are: 1. Does transcranial magnetic stimulation change effort task performance in Parkinson's Disease patients? 2. Is there a link between brain signals and apathy? Participants will * complete questionnaires and assessments * perform an effort task * have their brain activity recorded (EEG) * receive non-invasive brain stimulation (TMS) Researchers will compare two stimulation locations (experimental site and control site) to see if TMS of the experimental site has an effect on apathy. Participants will receive stimulation of both sites (during separate visits).