[1] Burke Rehabil Hosp, White Plains, NY USA
[2] Cornell Univ, Weill Med Coll, Dept Publ Hlth, New York, NY USA
[3] Dept Neurol & Neurosci, New York, NY USA
[4] Vet Hlth Adm, Dept Rehabil & Dev, Washington, DC USA
[5] Univ Maryland, Sch Med, Dept Phys Therapy, Baltimore, MD USA
[6] MIT, Dept Mech Engn, Cambridge, MA 02139 USA
[7] Dept Brain & Cognit Sci, Cambridge, MA USA