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Spaceflight missions to the International Space Station (ISS) expose astronauts to microgravity, radiation, isolation, and elevated carbon dioxide (CO 2), among other factors. Head down tilt bed rest (HDBR) is an Earth-based analog for spaceflight used to study body unloading, fluid shifts, and other factors unrelated to gravitational changes. While in space, astronauts need to use mental rotation strategies to facilitate their adaptation to the ISS environment. Therefore, spatial working memory is essential for crewmember performance. Although the effects of HDBR on spatial working memory have recently been studied, the results are still inconclusive. Here, we expand upon past work and examine the effects of HDBR with elevated CO 2 (HDBR + CO 2) on brain activation patterns during spatial working memory performance. In addition, we compare brain activation between 30 days of HDBR + CO 2 and 70 days of HDBR to test the isolated effect of CO 2. Eleven subjects (6 males, 5 females; mean age = 34 ± 8 years) underwent six functional magnetic resonance imaging (fMRI) sessions pre-, during, and post-HDBR + CO 2. During the HDBR + CO 2 intervention, we observed decreasing activation in the right middle frontal gyrus and left regions of the cerebellum, followed by post-intervention recovery. We detected several correlations between brain and behavioral slopes of change with the HDBR + CO 2 intervention. For example, greater increases in activation in frontal, temporal and parietal regions were associated with larger spatial working memory improvements. Comparing the HDBR + CO 2 group to data from our previous 70-day HDBR study, we found greater decreases in activation in the right hippocampus and left inferior temporal gyrus for the HDBR + CO 2 group over the course of the intervention. Together, these findings increase our understanding of the neural mechanisms of HDBR, elevated levels of CO 2 and spaceflight-related changes in spatial working memory performance.

Astronauts returning from spaceflight typically show transient declines in mobility and balance. Other sensorimotor behaviors and cognitive function have not been investigated as much. Here, we tested whether spaceflight affects performance on various sensorimotor and cognitive tasks during and after missions to the International Space Station (ISS). We obtained mobility (Functional Mobility Test), balance (Sensory Organization Test-5), bimanual coordination (bimanual Purdue Pegboard), cognitive-motor dual-tasking and various other cognitive measures (Digit Symbol Substitution Test, Cube Rotation, Card Rotation, Rod and Frame Test) before, during and after 15 astronauts completed 6 month missions aboard the ISS. We used linear mixed effect models to analyze performance changes due to entering the microgravity environment, behavioral adaptations aboard the ISS and subsequent recovery from microgravity. We observed declines in mobility and balance from pre- to post-flight, suggesting disruption and/or down weighting of vestibular inputs; these behaviors recovered to baseline levels within 30 days post-flight. We also identified bimanual coordination declines from pre- to post-flight and recovery to baseline levels within 30 days post-flight. There were no changes in dual-task performance during or following spaceflight. Cube rotation response time significantly improved from pre- to post-flight, suggestive of practice effects. There was also a trend for better in-flight cube rotation performance on the ISS when crewmembers had their feet in foot loops on the “floor” throughout the task. This suggests that tactile inputs to the foot sole aided orientation. Overall, these results suggest that sensory reweighting due to the microgravity environment of spaceflight affected sensorimotor performance, while cognitive performance was maintained. A shift from exocentric (gravity) spatial references on Earth toward an egocentric spatial reference may also occur aboard the ISS. Upon return to Earth, microgravity adaptions become maladaptive for certain postural tasks, resulting in transient sensorimotor performance declines that recover within 30 days.

Background: Individuals with Parkinson disease (PD) present balance and functional mobility disabilities that negatively affect the quality of life (QOL). Objective: To systematically review the effects of hydrotherapy on balance, functional mobility, QOL, and motor status in patients with PD. Design: Systematic review and meta-analysis. Participants: A total of 484 participants were included. The mean age of participants ranged from 54 to 78 years. The average duration of PD ranged from 3 to 10 years. Methods: MEDLINE (PubMed), Embase, Cochrane CENTRAL, SCOPUS, Scielo, Physiotherapy Evidence Database (PEDro), and Google Scholar were searched from inception to December 2017. Randomized controlled trials (RCT), non-RCT, and pre-post studies were included. Results: A total of 19 studies were identified, including eight RCTs, three non-RCTs, and eight pre-post studies. Our meta-analysis showed a moderate quality of evidence for positive effects of hydrotherapy combined or not with land-based therapy on balance (133 patients; MD = 2.00 [95% CI, 0.56 to 3.43; I 2 0%, P = .01]) and functional mobility (133 patients; MD = −1.08 [95% CI, −1.99 to −0.18; I 2 8%, P = .02]). However, hydrotherapy combined or not with land-based therapy did not improve QOL (76 patients; MD = −6.35 [95% CI, −13.04 to 0.33; I 2 7%, P = .06]) and motor status (140 patients; MD = −1.11 [95% CI, −3.27 to 1.04; I 2 0%, P = .31). The risk of bias across the included RCTs was low. Conclusions: Hydrotherapy, combined or not with other therapies, may improve balance and functional mobility of patients with PD when compared to land-based therapy alone or usual care.