This study will evaluate new magnetic resonance imaging (MRI ) methods using a MRI machine more powerful than those in most hospitals. MRI is a diagnostic tool that uses a large magnet and radio waves to produce images of the human body. It can also provide information about brain chemistry and physiology. This study will use the new MRI hardware and methods to measure blood flow and metabolism in regions of the brain during simple tasks, such as listening to tones or watching flashing checkerboards.

Healthy normal volunteers will undergo MRI scanning. For this procedure, the person lies on a stretcher that is moved into a MRI machine, which produces a strong magnetic field. A special lightweight coil is placed on the person's head to obtain better pictures. The scan time ranges from 20 minutes to 2 hours, with the average scan lasting between 45 and 90 minutes. Some persons will be asked to have a contrast agent called gadolinium DTPA injected into their arm through an intravenous catheter (a thin tube placed in a vein). This substance improves scan pictures and is often used in routine MRI brain scans.

During the MRI, the person may be asked to perform simple tasks, such as listening to tones or watching a screen, tapping fingers or moving a hand. More complex tasks may require thinking about tones or pictures and responding to them by pressing buttons.

The images produced in this study will be compared with those produced using standard MRI. The results will be used to develop improved imaging methods for better patient care and research.