THIS PROPOSAL OUTLINES THE PLAN FOR MONITORING THE PHYSIOLOGICAL AND ANATOMICAL EFFECTS OF TWO DIFFERENT REGIMENS OF INTERMITTENT CENTRIFUGATION INDUCED ARTIFICIAL GRAVITY WITH FOCUS ON THE BRAIN EYE AND VESTIBULAR SYSTEM RESPONSES. THE SPECIFIC AIMS WILL INCLUDE: 1. INTEGRATIVE EVALUATION OF THE CEREBRAL PHYSIOLOGICAL EFFECTS OF AG DURING THE 60 DAY BED REST PERIOD USING BETWEEN GROUP AND WITHIN GROUP COMPARISONS AND 2. ASSESSMENT OF THE ACUTE DYNAMIC CHANGES IN THE HUMAN BODY SYSTEMS RELATED TO THE CENTRIFUGATION REGIMEN. THE METHODS AND TECHNIQUES USED TO ACHIEVE THESE OBJECTIVES INCLUDE: NON-INVASIVE ASSESSMENT OF ICP CEREBRAL BLOOD FLOW CEREBRAL BLOOD VOLUME CSF FLOW AND VOLUMES OCULAR ANATOMY AND PHYSIOLOGY AND NEUROVESTIBULAR FUNCTION. THIS PROPOSAL WILL DELIVER AN INTEGRATED VIEW OF THE PHYSIOLOGICAL ANATOMICAL AND FUNCTIONAL EFFECTS OF INTERMITTENT CENTRIFUGATION (ARTIFICIAL GRAVITY) ON THE CEREBROVASCULAR OCULAR AND VESTIBULAR SYSTEMS. THIS WILL PROVIDE IMPORTANT INSIGHTS INTO THE EFFECTIVENESS OF THIS FORM OF ARTIFICIAL GRAVITY TO COUNTERACT THE HEADWARD FLUID SHIFTING OF HEAD DOWN TILT; WHICH MAY YIELD IMPORTANT KNOWLEDGE ABOUT THE FUTURE UTILITY OF THIS METHOD AS A COUNTERMEASURE FOR THE SPACE-FLIGHT INDUCED HEADWARD FLUID SHIFTS AND THE VIIP SYNDROME.