1. Department of Emergency Medicine, Stanford University, Stanford, CA 94304, USA
2. Department of Psychiatry, Stanford University, Stanford, CA 94304, USA
3. Department of Physical Medicine & Rehabilitation, University of Utah, Salt Lake City, UT 84108, USA
4. Department of Sports Medicine, Stanford University, Stanford, CA 94304, USA
5. Department of Neurosurgery, Brain Performance Center, Stanford University, Stanford, CA 94304, USA