Background:

- Different regions of the brain are activated when a person performs a task. Electroencephalograms (EEGs) and near-infrared spectroscopy (NIRS) are tests that detect changes in the brain. EEG looks at changes in electrical signals, and NIRS looks at changes in blood flow. These tests can detect local changes in brain activity in a safe and noninvasive way. Researchers want to study brain activity more closely by combining these tests.

Objectives:

- To use EEG and NIRS to study brain activity during specific tasks.

Eligibility:

- Healthy volunteers at least 18 years of age.

Design:

• Participants will be screened with a physical exam and medical history.
• Participants will have between one and five testing sessions. Each session will be 1 to 2 hours long. The tests given at each session will be determined by the researchers.
• Participants will have EEG and NIRS tests, given either separately or together. During these tests, participants will perform tasks of thinking and reasoning.
• Participants may also complete optional tests of thinking and reasoning. These tests will be given on paper or on a computer.

Objective: To record near-infrared optical signal (NIRS) simultaneously with EEG signal and correlate hemodynamic and neuronal responses, and to understand brain connectivity associated with cognitive functions using combined EEG/NIRS technology

Study population: 40 healthy volunteers

Design: The study will aim to capture the dynamics of brain interactions on two different scales by combing EEG (neuronal) and NIRS (hemodynamic) techniques. We will then correlate the two responses to study the brain connectivity in a more comprehensive way.

Outcome Measures: graded changes in blood flow and blood oxygenation, measured with NIRS, along with electrical signals recorded by EEG in response to different functional tasks.

Note: This study is sponsored by the Center for Neuroscience and Regenerative Medicine (CNRM). De-identified data including imaging data sent to CNRM may be shared with outside investigators or collaborators. This data may be used for a variety of research purposes. The Henry M. Jackson Foundation for the Advancement for Military Medicine (HJF), USUHS, or DOD representatives may also access data for audit purposes.

• INCLUSION CRITERIA:
• Age 18 years or greater.

EXCLUSION CRITERIA:

• Healthy volunteers with any skin disease.
• Past or present hematologic abnormality of Hgb < 9.0 gm/dl.
• Healthy volunteers with any past or present vascular disease.
• Have a history of substance abuse, psychiatric, or neurological disorders
• Any medical condition that, in the opinion of the Principal Investigator, would preclude the inclusion of a patient onto this research study.
• Unable or unwilling to give informed consent.