1. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
2. Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
3. Department of Exercise and Sport Science and University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
4. Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
5. Department of Center for Imaging Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
6. Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
7. Department of Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.