INCLUSION CRITERIA:
Normal adults, with at least a high school education, aged 18 to 65 years, will be recruited to participate in the study.
EXCLUSION CRITERIA:
Subjects will be excluded if they have evidence of, or a history of, learning disability, psychiatric condition, head trauma, seizures or other neurological condition, alcoholism or substance abuse, hypertension, or cardiovascular disease.
We will also exclude subjects with vision and/or hearing problems severe enough to interfere with testing.
Females with a positive pregnancy test will be excluded from neuroimaging studies.
All subjects will be questioned prior to MRI scanning for possible occupational exposure to metal slivers or shavings, which may have become accidentally lodged in the tissues of the head or neck. Those whose history is suggestive of such a problem will be excluded. Subjects with surgical clips or shrapnel in or near the brain or blood vessels, subjects with cochlear implants, subjects with any metallic body in the eye or CNS, and subjects with any form of implant wire or metal device which may concentrate radiofrequency fields will be excluded because of possible risks during MRI scanning.