NRA NNJ14ZSA001N-MIXEDTOPICS REQUESTS PROPOSALS IN THE AREA OF RISK CHARACTERIZATION AND MONITORING OF BEHAVIORAL HEALTH AND PERFORMANCE RELEVANT OUTCOMES TO DETERMINE THE EFFECTS OF 30 DAYS HEAD DOWN TILT BED REST IN A 0.5% CO2 ENVIRONMENT ON NEUROBEHAVIORAL SIGNS AND SYMPTOMS NEUROSTRUCTURAL AND NEUROFUNCTIONAL ALTERATIONS AND CHANGES IN COGNITIVE FUNCTION AND OPERATIONAL TASK PERFORMANCE. OUR NEUROMAPPING STUDIES MEASURE PRECISELY THESE METRICS IN A FLIGHT STUDY AND A 70 DAYS HEAD DOWN TILT BED REST STUDY UNDER NORMATIVE CONDITIONS. HERE OUR OVERARCHING GOAL IS TO QUANTIFY NEUROCOGNITIVE CHANGES AND ASSOCIATED NEURAL STRUCTURAL AND FUNCTIONAL ALTERATIONS OCCURRING AS A RESULT OF A 30 DAYS HEAD DOWN TILT BED REST PLUS 0.5% CO2 ENVIRONMENT SERVING AS A SPACEFLIGHT ANALOG EXPOSURE. WE WILL IDENTIFY THE RELATIONSHIP BETWEEN THESE NEURAL CHANGES AND BEHAVIORAL FUNCTION. OUR APPROACH UTILIZES CUTTING EDGE NEUROIMAGING TECHNIQUES AND A BROAD RANGING BATTERY OF SENSORY MOTOR AND COGNITIVE ASSESSMENTS TO INVESTIGATE NEUROPLASTIC AND MALADAPTIVE BRAIN CHANGES OCCURRING IN A SPACEFLIGHT ANALOG ENVIRONMENT. SUCCESS IN THIS ENDEAVOR WOULD 1) RESULT IN IDENTIFICATION OF THE UNDERLYING NEURAL MECHANISMS AND OPERATIONAL RISKS OF CHANGES IN BEHAVIOR WITH A SPACEFLIGHT ANALOG AND 2) IDENTIFY WHETHER A RETURN TO NORMATIVE BEHAVIORAL FUNCTION FOLLOWING BED REST IS ASSOCIATED WITH A RESTITUTION OF BRAIN STRUCTURE AND FUNCTION OR INSTEAD IS SUPPORTED BY SUBSTITUTION WITH COMPENSATORY BRAIN PROCESSES. MOREOVER ADDITION OF A CO2 GROUP WILL ENABLE US TO PARSE OUT THE MULTIPLE MECHANISMS CONTRIBUTING TO ANY SPACEFLIGHT INDUCED NEURAL STRUCTURAL AND BEHAVIORAL CHANGES THAT WE OBSERVE IN OUR ONGOING FLIGHT PROJECTS (NASA FLIGHT PROJECT SEIDLER PI; ILSRA FLIGHT STUDY STAHN PI) AND COMPARISON WITH OUR RECENTLY COMPLETED BED REST PROJECTS (SEIDLER AND STAHN PIS) WILL ALLOW US TO DELINEATE BRAIN AND BEHAVIORAL CHANGES OCCURRING WITH LONG TERM EXPOSURE TO SLIGHTLY ELEVATED CO2 LEVELS.