1. Department of Neurology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2. Department of Neurology, Washington University, School of Medicine, St Louis, Missouri, USA
3. Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri, USA
4. Department of Biostatistics and the Lineberger Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
5. Departments of Neurology, Anatomy and Neurobiology, Program in Physical Therapy, Program in Occupational Therapy and the Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri, USA