Detection and Amelioration of Gamma Oscillation Abnormalities in Blast-Related Brain Injury

Inclusion Criteria: * Research participants will be 50 veterans * Ages 18-65 years * Have experienced blast exposure * Recruited from the VA Translational Research Center for TBI and Stress Disorders (TRACTS) at the VA Boston Healthcare System (VABHS) * Half of the participants will have experienced blast exposure from a Close distance (\<10 m) * Half of the participants will have experienced blast exposure from a Far distance (\>10 m) * These groups will be matched on age and female/male ratio Exclusion Criteria: Initial exclusion criteria for TRACTS are: * History of neurological illness * Huntington's * Parkinson's * dementia, etc * History of seizure disorders unrelated to head injury * Current diagnosis of schizophrenia, bipolar, or other psychotic disorder * Self-reported severe depression or anxiety requiring hospitalization overnight, or current active homicidal and/or suicidal ideation with intent requiring crisis intervention * Cognitive disorder due to general medical condition other than TBI * Unstable psychological diagnosis (suspected psychotic or personality disorder) that would interfere with accurate data collection, determined by consensus of at least three doctoral-level psychologists. Additional exclusion criteria for participants in the present project will be: * Current alcohol or drug dependence, or abuse within the last 6 months (DSM-IV criteria) * Hearing impairments as assessed by audiometry