Study of New Magnetic Resonance Imaging Methods of the Brain

* INCLUSION CRITERIA: * 18 years of age and older * in good general health * able to understand the procedures and requirements and give informed consent EXCLUSION CRITERIA: All Subjects will undergo a neurological physical and answer the Healthy volunteer form, and the most-recent version of the NMR safety screening form A subject will be excluded if he/she: 1. has any metal implant or objects of unknown identity or composition, or if it s known to be non-compatible with MRI, such as pacemakers, medication pumps, aneurysm clips, metallic prosthesis (such as heart valves or cochlear implants), certain orthopedic implants (pins and rods), shrapnel, or small metal fragments in the eye; 2. has claustrophobia; 3. cannot lie comfortably for up to 120 minutes; 4. underwent brain surgery or suffered a traumatic head trauma; 5. has migraines that require medication; 6. has ever been hospitalized for a psychiatric disorder; 7. has medical health problems such as pulmonary or airway disease, heart failure, coronary artery disease, and uncontrolled hypertension which would require physiological monitoring during the scan; 8. has a history of any medical condition that could result in an emergency medical situation while undergoing the MRI scan; 9. has hearing problems which would make it difficult to tolerate scanner noise; 10. is pregnant; 11. has body/make-up tattoos (e.g. lips, eyebrows, eyeliner). Each tattoo will be considered on a case-to-case basis, taking into account of the age and location of the tattoo; 12. has a sleep apnea diagnosis; 13. has a neurological disorder, such as Stroke, Parkinson s, and Epilepsy; 14. a member of the NINDS Laboratory of Functional and Molecular Imaging. The contraindications to MRI at the various field strengths are almost identical, except the 7 T also excludes subjects with gold dental crowns.