1. Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
2. Parkinson's Disease Research, Education, and Clinical Center, Philadelphia Veterans Affairs Medical Center, Philadelphia, PA, USA
3. Division of Geriatric Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
4. Center for Sleep and Circadian Neurobiology and Division of Sleep Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
5. Avid Radiopharmaceuticals Inc., Philadelphia, PA, USA