1. Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, Massachusetts, USA.
2. Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Charlestown, Massachusetts, USA.
3. Department of Physical Medicine and Rehabilitation, Spaulding Research Institute, Charlestown, Massachusetts, USA.
4. MassGeneral Hospital for Children Sports Concussion Program, Boston, Massachusetts, USA.
5. Department of Psychology, University of Kentucky, Lexington, Kentucky, USA.