Longitudinal Changes in Cerebral Perfusion, Perivascular Space Volume, and Ventricular Volume in a Healthy Cohort Undergoing a Spaceflight Analog

Tidwell, Jamie; Taylor, J. Andrew; Collins, Heather; Chamberlin, Jordan; Barisano, Giuseppe; Sepehrband, Farshid; Turner, Matthew D; Gauthier, Gregory M.; Mulder, Edwin; Gerlach, Darius A.; Roberts, Donna R.

doi:10.3174/ajnr.a7949

Cited by 10 publications

(2 citation statements)

References 39 publications

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“…We have attempted to minimize the influence of one of the known threats to interpretive validity in neuroimaging studies in astronauts: the change in segmentation error bias driven by the redistribution of cerebrospinal fluid in the skull that we have described previously [39]. However, there are other potential threats to interpreting BOLD signals in astronauts after spaceflight, such as the changes in brain perfusion observed after a head-down bed rest study [68], a paradigm commonly employed as a spaceflight analog. Due to both known and unknown threats to the validity of our experiment, we recommend that these findings be treated as preliminary and interpreted with caution.…”

Section: Discussionmentioning

confidence: 99%

Neurocognitive Adaptations for Spatial Orientation and Navigation in Astronauts

Burles,

Iaria

2023

Brain Sciences

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Astronauts often face orientation challenges while on orbit, which can lead to operator errors in demanding spatial tasks. In this study, we investigated the impact of long-duration spaceflight on the neural processes supporting astronauts’ spatial orientation skills. Using functional magnetic resonance imaging (fMRI), we collected data from 16 astronauts six months before and two weeks after their International Space Station (ISS) missions while performing a spatial orientation task that requires generating a mental representation of one’s surroundings. During this task, astronauts exhibited a general reduction in neural activity evoked from spatial-processing brain regions after spaceflight. The neural activity evoked in the precuneus was most saliently reduced following spaceflight, along with less powerful effects observed in the angular gyrus and retrosplenial regions of the brain. Importantly, the reduction in precuneus activity we identified was not accounted for by changes in behavioral performance or changes in grey matter concentration. These findings overall show less engagement of explicitly spatial neurological processes at postflight, suggesting astronauts make use of complementary strategies to perform some spatial tasks as an adaptation to spaceflight. These preliminary findings highlight the need for developing countermeasures or procedures that minimize the detrimental effects of spaceflight on spatial cognition, especially in light of planned long-distance future missions.

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Section: Discussionmentioning

confidence: 99%

Neurocognitive Adaptations for Spatial Orientation and Navigation in Astronauts

Burles,

Iaria

2023

Brain Sciences

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“…A well-recognised terrestrial microgravity analogue is head-down tilt, which simulates the cephalad fluid shifts. In a recent head-down tilt study, there was an increase in ventricular and perivascular space volume suggesting glymphatic dysfunction but decreased cerebral blood flow 16 . Despite the findings of decreased blood flow in head-down tilt experiments, there is evidence for an increase in the cerebral blood flow during spaceflight in the literature.…”

Section: Physiology Of Sansmentioning

confidence: 94%

A perspective on the evidence for glymphatic obstruction in spaceflight associated neuro-ocular syndrome and fatigue

Bateman,

Bateman

2024

npj Microgravity

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Spaceflight associated neuro-ocular syndrome (SANS) alters the vision of astronauts during long-duration spaceflights. Previously, the current authors have discussed the similarities and differences between SANS and idiopathic intracranial hypertension to try to elucidate a possible pathophysiology. Recently, a theory has been advanced that SANS may occur secondary to failure of the glymphatic system caused by venous dilatation within the brain and optic nerves. There is recent evidence to suggest glymphatic obstruction occurs in childhood hydrocephalus, multiple sclerosis and syringomyelia due to venous outflow dilatation similar to that proposed in SANS. The purpose of the current paper is to discuss the similarities and differences between the known CSF and venous pathophysiology in SANS with these other terrestrial diseases, to see if they can shed any further light on the underlying cause of this microgravity-induced disease.

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