Head Down Tilt Bed Rest Plus Elevated CO2 as a Spaceflight Analog: Effects on Cognitive and Sensorimotor Performance

Lee, Jessica; Dios, Yiri De; Kofman, I. S.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.; Seidler, Rachael D.

doi:10.3389/fnhum.2019.00355

Cited by 53 publications

(72 citation statements)

References 49 publications

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“…At p < 0.0005 and k = 10, there were no regions of intercept or slope difference between the SANS and no-SANS participants. We previously found that SANS individuals increased their reliance on visual information during balance from pre-to post-HDBR + CO 2 (Lee et al, 2019a); that is, SANS subjects had greater increases in their ratio of eyes open balance compared to eyes closed balance. Here we identified multiple frontal, parietal, temporal, and occipital regions where the SANS subjects showed stronger correlations with this balance ratio score compared to the no-SANS subjects (Figure 8 and Table 7).…”

Section: Sans Vs No-sans Group Differencesmentioning

confidence: 94%

“…passed a minimum physical fitness standard (i.e., an Air Force Class III equivalent physical examination) to participate (Lee et al, 2019a).…”

Section: Participantsmentioning

confidence: 99%

“…Each of these balance tasks is described in Section "Balance Testing." We selected to compare brain-behavior correlations only for this ratio score here because we previously identified significant differences between the two SANS subgroups on this measure, in which SANS individuals showed greater increases from preto post-HDBR + CO 2 in their reliance on vision during balance compared to no-SANS individuals (Lee et al, 2019a). One of the five SANS subjects was excluded from this analysis due to outlier values for the balance-eyes closed condition (described in Section "Balance Testing").…”

Section: Sans Versus No-sans Group Comparisonsmentioning

confidence: 99%

“…Although the HDBR + CO 2 participants completed a battery of neurocognitive and sensorimotor assessments at each time point, here we focus on only mobility and balance testing, as these tasks were the most directly related to vestibular processing. We have previously published comprehensive behavioral profiles for both the HDBR + CO 2 (Lee et al, 2019a) and HDBR groups (Koppelmans et al, 2015), as well as vestibular brain-behavior correlations for the HDBR group (Yuan et al, 2018b).…”

Section: Mobility and Balance Testing: Hdbr + Co 2 Cohort Onlymentioning

confidence: 99%

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Neural Correlates of Vestibular Processing During a Spaceflight Analog With Elevated Carbon Dioxide (CO2): A Pilot Study

Hupfeld

Lee

Gadd

et al. 2020

Front. Syst. Neurosci.

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Astronauts return to Earth from spaceflight missions with impaired mobility and balance; recovery can last weeks postflight. This is due in large part to the altered vestibular signaling and sensory reweighting that occurs in microgravity. The neural mechanisms of spaceflight-induced vestibular changes are not well understood. Head-down-tilt bed rest (HDBR) is a common spaceflight analog environment that allows for study of body unloading, fluid shifts, and other consequences of spaceflight. Subjects in this context still show vestibular changes despite being in Earth's gravitational environment, potentially due to sensory reweighting. Previously, we found evidence of sensory reweighting and reduced neural efficiency for vestibular processing in subjects who underwent a 70-day HDBR intervention. Here we extend this work by evaluating the impact of HDBR paired with elevated carbon dioxide (CO 2) to mimic International Space Station conditions on vestibular neural processing. Eleven participants (6 males, 34 ± 8 years) completed 30 days of HDBR combined with 0.5% atmospheric CO 2 (HDBR + CO 2). Participants underwent six functional magnetic resonance imaging (fMRI) sessions pre-, during, and post-HDBR + CO 2 while we measured brain activity in response to pneumatic skull taps (a validated method of vestibular stimulation). We also measured mobility and balance performance several times before and after the intervention. We found support for adaptive neural changes within the vestibular system during bed rest that subsequently recovered in several cortical and cerebellar regions. Further, there were multiple brain regions where greater pre-to postdeactivation was associated with reduced pre-to post-balance declines. That is, increased deactivation of certain brain regions associated with better balance post-HDBR + CO 2. We also found that, compared to HDBR alone (n = 13 males; 29 ± 3 years) HDBR + CO 2 is associated with greater increases in activation of multiple frontal, parietal, and temporal regions during vestibular stimulation. This suggests interactive or additive effects of bed rest and elevated CO 2. Finally, we found stronger correlations between pre-to post-HDBR + CO 2 brain changes and dependence on the visual system during balance for subjects who developed signs of Spaceflight-Associated Neuro-ocular Syndrome

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Section: Sans Vs No-sans Group Differencesmentioning

confidence: 94%

“…passed a minimum physical fitness standard (i.e., an Air Force Class III equivalent physical examination) to participate (Lee et al, 2019a).…”

Section: Participantsmentioning

confidence: 99%

Section: Sans Versus No-sans Group Comparisonsmentioning

confidence: 99%

Section: Mobility and Balance Testing: Hdbr + Co 2 Cohort Onlymentioning

confidence: 99%

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Neural Correlates of Vestibular Processing During a Spaceflight Analog With Elevated Carbon Dioxide (CO2): A Pilot Study

Hupfeld

Lee

Gadd

et al. 2020

Front. Syst. Neurosci.

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“…Recent long-duration head-down tilt studies have shown potential for recreating SANS signs in terrestrial cohorts 51 . However, SANS is considered a pathology unique to spaceflight.…”

Section: Spaceflight-associated Neuro-ocular Syndromementioning

confidence: 99%

Red risks for a journey to the red planet: The highest priority human health risks for a mission to Mars

et al. 2020

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NASA’s plans for space exploration include a return to the Moon to stay—boots back on the lunar surface with an orbital outpost. This station will be a launch point for voyages to destinations further away in our solar system, including journeys to the red planet Mars. To ensure success of these missions, health and performance risks associated with the unique hazards of spaceflight must be adequately controlled. These hazards—space radiation, altered gravity fields, isolation and confinement, closed environments, and distance from Earth—are linked with over 30 human health risks as documented by NASA’s Human Research Program. The programmatic goal is to develop the tools and technologies to adequately mitigate, control, or accept these risks. The risks ranked as “red” have the highest priority based on both the likelihood of occurrence and the severity of their impact on human health, performance in mission, and long-term quality of life. These include: (1) space radiation health effects of cancer, cardiovascular disease, and cognitive decrements (2) Spaceflight-Associated Neuro-ocular Syndrome (3) behavioral health and performance decrements, and (4) inadequate food and nutrition. Evaluation of the hazards and risks in terms of the space exposome—the total sum of spaceflight and lifetime exposures and how they relate to genetics and determine the whole-body outcome—will provide a comprehensive picture of risk profiles for individual astronauts. In this review, we provide a primer on these “red” risks for the research community. The aim is to inform the development of studies and projects with high potential for generating both new knowledge and technologies to assist with mitigating multisystem risks to crew health during exploratory missions.

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Ophthalmic changes in a spaceflight analog are associated with brain functional reorganization

McGregor

Lee

Mulder

et al. 2021

Human Brain Mapping

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Following long‐duration spaceflight, some astronauts exhibit ophthalmic structural changes referred to as Spaceflight Associated Neuro‐ocular Syndrome (SANS). Optic disc edema is a common sign of SANS. The origin and effects of SANS are not understood as signs of SANS have not manifested in previous spaceflight analog studies. In the current spaceflight analog study, 11 subjects underwent 30 days of strict head down‐tilt bed rest in elevated ambient carbon dioxide (HDBR+CO2). Using functional magnetic resonance imaging (fMRI), we acquired resting‐state fMRI data at 6 time points: before (2), during (2), and after (2) the HDBR+CO2 intervention. Five participants developed optic disc edema during the intervention (SANS subgroup) and 6 did not (NoSANS group). This occurrence allowed us to explore whether development of signs of SANS during the spaceflight analog impacted resting‐state functional connectivity during HDBR+CO2. In light of previous work identifying genetic and biochemical predictors of SANS, we further assessed whether the SANS and NoSANS subgroups exhibited differential patterns of resting‐state functional connectivity prior to the HDBR+CO2 intervention. We found that the SANS and NoSANS subgroups exhibited distinct patterns of resting‐state functional connectivity changes during HDBR+CO2 within visual and vestibular‐related brain networks. The SANS and NoSANS subgroups also exhibited different resting‐state functional connectivity prior to HDBR+CO2 within a visual cortical network and within a large‐scale network of brain areas involved in multisensory integration. We further present associations between functional connectivity within the identified networks and previously identified genetic and biochemical predictors of SANS. Subgroup differences in resting‐state functional connectivity changes may reflect differential patterns of visual and vestibular reweighting as optic disc edema develops during the spaceflight analog. This finding suggests that SANS impacts not only neuro‐ocular structures, but also functional brain organization. Future prospective investigations incorporating sensory assessments are required to determine the functional significance of the observed connectivity differences.

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Head Down Tilt Bed Rest Plus Elevated CO2 as a Spaceflight Analog: Effects on Cognitive and Sensorimotor Performance

Cited by 53 publications

References 49 publications

Neural Correlates of Vestibular Processing During a Spaceflight Analog With Elevated Carbon Dioxide (CO2): A Pilot Study

Neural Correlates of Vestibular Processing During a Spaceflight Analog With Elevated Carbon Dioxide (CO2): A Pilot Study

Red risks for a journey to the red planet: The highest priority human health risks for a mission to Mars

Ophthalmic changes in a spaceflight analog are associated with brain functional reorganization

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