This study is designed to understand how we see visual patterns and how these patterns lead to eye movements.

Normal volunteers participating in this study face a screen on which spots or patterns of light are projected. They are asked to respond to the patterns by voice, eye movements or hand movements. Eye and lid movements are recorded in one of the following ways:

1. Electro-oculogram < small disc electrodes taped to the skin near each eye measure the eye movements as the eyes change position.
2. Infrared detector < an infrared beam is reflected off the eye and picked up by detectors that record the eye movements.
3. Contact lens ring < a smooth plastic ring is placed on the white of the eye surrounding the cornea and eye position is measured using a magnetic coil.

Study sessions last less than four hours.

The purpose of this protocol is to study the physiology of the visuo-motor system in normal humans. This will be accomplished by recording eye movements and other responses (such as reaction time to bar press or verbal responses) to differing stimuli. The stimuli will be primarily visual but may include auditory or tactile stimuli.

• INCLUSION CRITERIA:

Normal adult volunteers age 18 and over are included.

Only normal volunteers are studied under this protocol. Normal volunteers are recruited from the NIH volunteer office and the NIH web page. Women and minorities are actively recruited.