Participants will be evaluated before the chamber sessions, at 13 weeks, and at 6 months. Assessments include self-administered questionnaires, neuropsychological function, neuroimaging, a brief neurological examination, and a neuro-optometry evaluation. These outcome tools will measure symptoms and deficit at the time of enrollment and subsequent evaluations, and provide insight into whether hyperbaric oxygen can play a role in recovery from mild traumatic brain in-jury.