Brain connectivity and behavioral changes in a spaceflight analog environment with elevated CO.

Astronauts are exposed to microgravity and elevated CO levels onboard the International Space Station. Little is known about how microgravity and elevated CO combine to affect the brain and sensorimotor performance during and after spaceflight. Here we examined changes in resting-state functional connectivity (FC) and sensorimotor behavior associated with a spaceflight analog environment. Participants underwent 30 days of strict 6 head-down tilt bed rest with elevated ambient CO (HDBR+CO). Resting-state functional magnetic resonance imaging and sensorimotor assessments were collected 13 and 7 days prior to bed rest, on days 7 and 29 of bed rest, and 0, 5, 12, and 13 days following bed rest. We assessed the time course of FC changes from before, during, to after HDBR+CO. We then compared the observed connectivity changes with those of a HDBR control group that underwent HDBR in standard ambient air. Moreover, we assessed associations between post-HDBR+CO FC changes and alterations in sensorimotor performance. HDBR+CO was associated with significant changes in functional connectivity between vestibular, visual, somatosensory and motor brain areas. Several of these sensory and motor regions showed post-HDBR+CO FC changes that were significantly associated with alterations in sensorimotor performance. We propose that these FC changes reflect multisensory reweighting associated with adaptation to the HDBR+CO microgravity analog environment. This knowledge will further improve HDBR as a model of microgravity exposure and contribute to our knowledge of brain and performance changes during and after spaceflight.