1. J.O. Helminski, PT, PhD, is Associate Professor, Department of Physical Therapy, Midwestern University, 555 31st St, Downers Grove, IL 60515 (USA).
2. D.S. Zee, MD, is Professor, Departments of Neurology, Ophthalmology, Otolaryngology, and Pathology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland.
3. I. Janssen, PhD, is Assistant Professor, Department of Preventive Medicine, Rush University Medical Center, Chicago, Illinois.
4. T.C. Hain, MD, is Professor, Departments of Physical Therapy and Human Movement Science, Otolaryngology, and Neurology, Northwestern University Medical School, Chicago, Illinois.