The Effects of Long Duration Head Down Tilt Bed Rest on Neurocognitive Performance: Extent, Longevity, & Neural Bases

• Aim 1- Identify changes in brain structure, function, and network integrity as a function of prolonged head down tilt bed rest / spaceflight and characterize their time course.• Aim 2- Specify relationships between structural and functional brain changes and performance and characterize their time course.