The purpose of this investigation is to develop improved magnetic resonance imaging (MRI) techniques and hardware for studying brain function. MRI is a diagnostic tool that provides information about brain chemistry and physiology. This study will evaluate new MRI methods for monitoring blood flow to regions of the brain in response to simple tasks. The MRI machine used in this study is more powerful than those in most hospitals, permitting a higher visual resolution.

Normal healthy volunteers over 18 years old may be eligible for this study. Candidates will be screened with a medical history and questionnaire, and a neurological examination. Study participants will have a yearly MRI scan. For this procedure, the subject lies on a stretcher that is moved into a donut-shaped machine with a strong magnetic field. A lightweight circular or rectangular coil-a device that improves the quality of the images-may be placed on the head. The scan time varies from 20 minutes to 3 hours; most scans last between 45 and 90 minutes. During the scan, the subject may perform simple tasks, such as listening to tapes, tapping a finger, moving a hand, watching a screen, or smelling a fragrance. More complex tasks may require thinking about tones or pictures and responding to them by pressing buttons.

Information from this study will be used to develop better imaging methods that will, in turn, permit a greater understanding of normal and abnormal brain behaviors.

The goal of this protocol is to improve the spatial resolution in MRI studies of the changes in hemodynamics that occur in the central nervous system (CNS) in healthy controls in response to sensory, motor, or cognitive stimulation.

CNS functional changes will be characterized by measuring blood flow, blood transit time, and blood oxygenation. These studies are required in order to develop and implement new imaging techniques for research and clinical applications. The NIMH/NINDS recently acquired a 3.0 T whole body magnetic resonance (MR) unit, located in the In Vivo NMR Research Center. This complements the already existing 1.5 T MR units.

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• Ogawa S, Tank DW, Menon R, Ellermann JM, Kim SG, Merkle H, Ugurbil K. Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging. Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):5951-5.
• Detre JA, Leigh JS, Williams DS, Koretsky AP. Perfusion imaging. Magn Reson Med. 1992 Jan;23(1):37-45.

• INCLUSION CRITERIA:

Any neurologically and psychiatrically normal, male or female, healthy volunteer over 18 years old. Subjects must be capable of understanding the procedures and requirements of this study. Subjects must be willing to sign an informed consent document.

EXCLUSION CRITERIA:

A subject will be excluded if he/she has a contraindication to MR scanning such as the following: pregnancy, aneurysm clip; implanted neural stimulator; implanted cardiac pacemaker or auto-defibrillator; cochlear implant; ocular foreign body (e.g. metal shavings or insulin pump) and any pre-existing eye conditions. Subjects who underwent brain surgery, who have a neurological lesion, a psychiatric history or a history of migraine will also be excluded from this study. The contraindications to MRI at 1.5 T and 3.0 T are identical.