1. Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, Illinois;
2. Departments of Physiology, Physical Medicine and Rehabilitation, and Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois;
3. Department of Physiology & Biophysics, University of Washington, Seattle, Washington; and
4. Department of Physical Medicine and Rehabilitation, Northwestern University, Feinberg School of Medicine, Chicago, Illinois