Two catheters (small plastic tubes) are placed into veins in the subject's arms for injecting [18F]FA85380 and for collecting blood samples during the scan. A third catheter is placed into a wrist artery to obtain arterial blood during the scan. With the catheters in place, the subject lies down on the scanner bed with his or her head placed in a special mask that limits movement during the brain scan. The scan begins with an initial transmission scan to measure tissue attenuation for about 15 minutes, after which the [18F]FA85380 is injected and the actual PET scan starts. The entire procedure takes about 4 hours, including 2.5 hours of continuous scanning sessions, during which the subject is required to lie still. The second scan period start after one hour rest period where subjects can relax out of the scanner, and last 30 minutes. They are monitored throughout the procedure. Vital signs are measured and electrocardiogram is taken before and after injection of the tracer. At the end of the scanning, additional blood and urine samples are collected. Subjects are asked to urinate after each scanning session to lessen the radioactivity in the body.