ABSTRACT
Astronauts are exposed to microgravity and elevated CO2 levels onboard the International Space Station. Little is known about how microgravity and elevated CO2 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 CO2 (HDBR+CO2). 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+CO2. We then compared the observed connectivity changes with those of a HDBR control group, which underwent HDBR in standard ambient air. Moreover, we assessed associations between post-HDBR+CO2 FC changes and alterations in sensorimotor performance. HDBR+CO2 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+CO2 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+CO2 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 Interest Statement
The authors have declared no competing interest.
Footnotes
HRM analyzed fMRI data and brain-behavior associations. JKL and YED analyzed behavioral data. JKL collected data. JKL, NEG, ISK set up the experiment. RDS, ERM, JJB, APM designed the experiment and secured funding. HRM drafted the manuscript. HRM, JKL, ERM, JJB, RDS edited the manuscript.
This study was supported by NASA grant #80NSSC17K0021. HRM was supported by a NSERCpostdoctoral fellowship and a NASA Human Research Program grant augmentation.MRI files for this study will be placed in the NASA data repository upon study completion.