Реферат: During long-duration spaceflight, the brain is profoundly affected by various factors, including microgravity, space radiation, social isolation, confinement, and circadian disruption. These factors induce structural and functional alterations as the brain develops new and potentially compensatory mechanisms to adapt to the space environment. While functional and structural alterations have been broadly investigated, changes in the structure-function relationship have remained largely unexplored. Addressing this gap may pave the way for a better understanding of the underlying mechanisms that influence cognitive and behavioral outcomes post-spaceflight. Eighteen cosmonauts (age = 44.92 [SD=5.64]) engaged in long-duration space missions to the International Space Station consented to participate in the study. Ten minutes of resting-state fMRI and diffusion-weighted images were acquired at three time points: before the mission (Pre), shortly after (Post), and approximately 8 months later (follow-up). Thirteen healthy participants (age = 42.55 [SD=6.11]) matched for age, gender, education, and handedness were also included as controls. The well-defined structural decoupling index (SDI) from the Graph Signal Processing (GSP) framework was used to calculate the regional decoupling of functional data from the structure. An increased SDI value signifies a decoupling of functional activity from the underlying structure, meaning that the regions that are structurally connected have anti-correlated functional activity. On the other hand, a decreased SDI value signifies that the functional activity is coupled to the structure, meaning that regions that are structurally connected show highly correlated activity. A linear mixed model was applied to compare the SDI values considering the interaction of time and group as the fixed effect and subjects as the random effect for pre- and post-flight. For significantly altered regions, a longitudinal analysis was performed by fitting a linear mixed model to the SDI values. P-values were FDR-corrected. The interaction between Time and Group showed a significant effect on the SDI measure of the left insular cortex and right superior parietal lobule. Insular cortex activity showed a higher SDI, and the SPL showed a lower SDI in cosmonauts postflight. We further observed that coupling measures change significantly for both the insular cortex and the SPL. In contrast, the decoupling index showed no significant alteration. Longitudinal analysis showed no recovery to the baseline value. The left insular cortex is a part of the salience network, related to sensory perception, vestibular processing, interoception, and motor function, previously found to show reduced resting-state functional connectivity and decreased volume after spaceflight. Observing an increased SDI in this region, we hypothesize that the brain use an accommodating mechanism to keep the optimal functioning regardless of structural changes, which is vital in a new environment with conflicting and unfamiliar sensory stimuli. We also found decreased SDI value in the SPL related to audio-visual multisensory integration and processing. A decreased SDI measure of the SPL can be associated with the new need of the brain to integrate and process multisensory inputs faster than normal conditions in response to non-experienced environmental circumstances.

Библиографическая ссылка: Mortaheb S. , Jillings S. , Jeurissen B. , Schoenmaekers C. , Nosikova I. , Tomilovskaya E. , Rukavishnikov I. , Petrovichev V. , Makovskaya L. , Ryabova A. , Pechenkova E. , Demertzi A. , Wuyts F.
CORTICAL STRUCTURE-FUNCTION DECOUPLING ALTERATIONS AFTER LONG-DURATION SPACEFLIGHT
NASA Human Research Program Investigators 28-31 Jan 2025