Research by LSA Psychologist Shows That Space Flight Changes Astronauts' Brains
"We found large regions of gray matter volume decreases, which could be related to redistribution of cerebrospinal fluid in space," said Seidler. "Gravity is not available to pull fluids down in the body, resulting in so-called puffy face in space. This may result in a shift of brain position or compression."
Seidler also found that gray matter increased in certain areas of the brain associated with leg movement.