Inclusion Criteria:(Control Group: 6 healthy, normal couple pairs)  No clinical diagnosis of PD Age 25 years old and older Physically independent, ambulatory Women of childbearing potential will confirm a negative pregnancy test and must practice effective contraception during the period of pilot study. In addition, male subjects who have a partner of childbearing age should practice effective contraception.  Inclusion Criteria for Female Partner in Couple Pairs in Parkinson's Group who has Parkinson's Disease  Clinical diagnosis of PD in female partner Age 30 years old and older Physically independent, ambulatory Hoehn and Yahr score of I-III inclusive. On stable antiparkinsonian medication for at least one month Women of childbearing potential will confirm a negative pregnancy test and must practice effective contraception during the period of pilot study. In addition, male subjects who have a partner of childbearing age should practice effective contraception.  Inclusion Criteria for Second Partner with No PD in Couple Pairs in Parkinson's Group  No clinical diagnosis of PD Age 25 years old and older Physically independent, ambulatory Women of childbearing potential will confirm a negative pregnancy test and must practice effective contraception during the period of pilot study. In addition, male subjects who have a partner of childbearing age should practice effective contraception.  Exclusion Criteria: (In Control Couple Pairs and in Couple Pairs Group in which the Female member has PD)  Previous brain surgery. Cognitive impairment by evaluation or known score on Mini-Mental Status examination of 25 or lower. Wheelchair-bound or bed-ridden, non-ambulatory. Intracranial abnormalities that may complicate interpretation of the brain scans (e.g., stroke, tumor, vascular abnormality affecting the target area). Diagnosis of traumatic brain injury with significant impairment. Any medical disorder or physical condition that could reasonably be expected to interfere with the assessment of parkinsonian syndrome symptoms, or with any of the study assessments including the PET-MRI imaging. No metal in their body that would prevent MRI scanning (as determined by the PI). Subjects with evidence of a significant psychiatric disorder by history/examination that would prevent completion of the study will not be allowed to participate. Subjects with current alcohol or drug abuse. Pregnant or lactating women. Enrollment in active clinical trial/ experimental therapy within the prior 30 days. Pending surgery during the course of the study. History of thrombocytopenia or clotting disorders. Cancer patients receiving active chemotherapy. History of uncontrolled diabetes and/or thyroid conditions. History of severe kidney disease (if a subject reports this problem, a serum creatinine will be checked to assess glomerular filtration rate (GFR) and if it is less than 30, they will be excluded).