1. Department of Neurology and Clinical Neuroscience, Stanford University School of Medicine, Palo Alto, CA 94305, USA
2. Department of Rehabilitation and Regenerative Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
3. Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
4. Center for Rehabilitation Services, Stanford Children’s Health, Stanford University, Palo Alto, CA 94305, USA
5. Center for Experimental Neurotherapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
6. Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
7. Departments of Neurology and Pediatrics, Columbia University Irving Medical Center, New York, NY 10032, USA
8. Biogen, Maidenhead SL6 4AY, Berkshire, UK
9. Biogen, Cambridge, MA 02142, USA