1. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
2. Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, USA
3. Department of Neurology, National Neuroscience Institute, Singapore
4. Department of Neurology, University of Texas, Southwestern, Dallas, TX, USA
5. Department of Molecular Microbiology and Immunology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
6. Biogen-IDEC, Cambridge, MA, USA