Multimodal Magnetic Resonance Imaging Reveals the Combined Effects of Simulated Microgravity and Space Radiation on Brain Structure and Function

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The extreme environmental factors in space, particularly microgravity and radiation, significantly impact the brain, yet the specific changes and potential risks from their combined effects remain unclear. Here, we investigated the combined effects of simulated microgravity and radiation on brain structure and function using high-resolution multimodal magnetic resonance imaging protocols. Additionally, we developed a super-resolution vascular reconstruction method to explore the impact of various space environments on the cerebral vascular structures. The results showed that combined space stressors were associated with smaller ventricular volume and greater gray matter volume in the hippocampus, striatum and thalamus. Notably, white matter integrity and functional connectivity in brain regions associated with motor behavior, cognition, and neuroendocrine function showed a significant reduction. The brain responded differently to simulated microgravity and radiation: super-resolution vascular reconstruction revealed an increase in cerebral vascular volume under simulated microgravity, while functional connectivity was more sensitive to radiation. This study is the first to systematically reveal the combined effects of simulated microgravity and radiation on brain structure and function using multimodal imaging techniques. Our results demonstrate that the combined effects of simulated microgravity and radiation lead to novel and complex changes in brain structure and function. This highlights key areas that need focused attention under the challenging environmental conditions of long-term deep space exploration, providing crucial insights for brain health in future deep space missions.