1. Department of Neurosurgery, The Paralysis Center, Massachusetts General Hospital, Boston, Massachusetts, USA;
2. Rehabilitation Sciences, MGH Institute of Health Professions, Boston, Massachusetts, USA;
3. Physical Therapy Department, Spaulding Rehabilitation Hospital, Boston, Massachusetts, USA;
4. Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi, USA;
5. Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, Mississippi, USA;
6. Physical Therapy Department, Wentworth-Douglass Hospital, Dover, New Hampshire, USA;
7. Harvard Medical School, Cambridge, Massachusetts, USA;
8. Brigham and Women's Hospital, Boston, Massachusetts, USA