Spaceflight-induced neuroplasticity in humans as measured by MRI: what do we know so far?

Abstract

Space travel poses an enormous challenge on the human body; microgravity, ionizing radiation, absence of circadian rhythm, confinement and isolation are just some of the features associated with it. Obviously, all of the latter can have an impact on human physiology and even induce detrimental changes. Some organ systems have been studied thoroughly under space conditions, however, not much is known on the functional and morphological effects of spaceflight on the human central nervous system. Previous studies have already shown that central nervous system changes occur during and after spaceflight in the form of neurovestibular problems, alterations in cognitive function and sensory perception, cephalic fluid shifts and psychological disturbances. However, little is known about the underlying neural substrates. In this review, we discuss the current limited knowledge on neuroplastic changes in the human central nervous system associated with spaceflight (actual or simulated) as measured by magnetic resonance imaging-based techniques. Furthermore, we discuss these findings as well as their future perspectives, since this can encourage future research into this delicate and intriguing aspect of spaceflight. Currently, the literature suffers from heterogeneous experimental set-ups and therefore, the lack of comparability of findings among studies. However, the cerebellum, cortical sensorimotor and somatosensory areas and vestibular-related pathways seem to be involved across different studies, suggesting that these brain regions are most affected by (simulated) spaceflight. Extending this knowledge is crucial, especially with the eye on long-duration interplanetary missions (e.g. Mars) and space tourism.

Pain and Vertebral Dysfunction in Dry Immersion: A Model of Microgravity Simulation Different from Bed Rest Studies

“…In general, simulated microgravity studies do not include factors such as launch stress, acceleration, excitement, anxiety, prolonged isolation, and environmental parameters such as light intensity, light/dark cycles, pressure, and radiation exposure. For example, spaceflights are associated with increased stress levels, while DI and HDBR are associated with boredom due to monotony and immobilization [28]. So all or any of these factors constitute limitations, which could affect the interpretation of the results of simulation studies.…”

Expedition Cognition: A Review and Prospective of Subterranean Neuroscience With Spaceflight Applications

“…Psychology, mental heath, team performance and group interactions in space are reviewed in (Suedfeld and Steel, 2000 ; Manzey, 2004 ; Kanas and Manzey, 2008 ; Kanas, 2015 ; Salas et al, 2015 ; Pagel and Choukèr, 2016 ; Sandal, 2018 ). For a discussion of current knowledge on neuroplastic changes in the human central nervous system associated with spaceflight (actual or simulated) as measured by magnetic resonance imaging-based techniques (see Van Ombergen et al, 2017 ). Cognitive functions, human error, and workload and fatigue are relevant to expedition cognition and are amenable to study in the cave environment as discussed here; useful references for further reading include (De La Torre et al, 2012 ; Gore, 2018 ; Kanki, 2018a ).…”

Effects of Microgravity on Human Physiology

“…In 2017, a review on these MRI changes associated with spaceflight (actual or simulated) was reported. Van Ombergen et al [32] discussed neuroplastic changes in the central nervous system and concluded that the cerebellum, cortical motor areas, and vestibular-related pathways are highly involved, demonstrating that these brain regions are indeed affected by actual and simulated spaceflight. Structural studies are now in progress, and functional relationships are under investigation.…”