Brain connectivity and behavioral changes in a spaceflight analog environment with elevated CO 2 .

Astronauts are exposed to microgravity and elevated CO ₂ levels onboard the International Space Station. Little is known about how microgravity and elevated CO ₂ 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 ^o head-down tilt bed rest with elevated ambient CO ₂ (HDBR+CO ₂ ). 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 ₂ . 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 ₂ FC changes and alterations in sensorimotor performance. HDBR+CO ₂ 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 ₂ 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 ₂ 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.
Competing Interests: Declarations of Competing Interest None.
(Copyright © 2020. Published by Elsevier Inc.)