- The study population will include 30 males and females with persistent post-concussive symptoms continuing up to 7 days after TBI. Participants will be military service members or civilians presenting as outpatients for clinical management of TBI or post-concussive symptoms at the Center for Neuroscience and Regenerative Medicine (CNRM)-affiliated hospitals. These include the Walter Reed National Military Medical Center (WRNMMC), Suburban Hospital (SH), and Washington Hospital Center (WHC).