The purpose of the research study is to collect information about brain function and
structure among active duty military personnel or civilians who are healthy. Researchers want
to develop a database from normal volunteers that will be used in comparison with a similar
database from active duty military with post-concussive syndrome (PCS) from a mild traumatic
brain injury. Findings from this study may be used to design larger studies that will
evaluate whether hyperbaric oxygen treatments actually improve PCS.

Participants in this study will undergo numerous tests to assess physical, mental, and
intellectual health and how they might change over time. Participants will wear heart and
activity monitors, undergo brain imaging, provide blood and urine for laboratory testing, and
have vision, hearing, balance, and muscle function tests. They will also complete a number of
questionnaires and interviews. This battery of tests will be repeated twice more over the
course of 6 months.