During spaceflight, the central nervous system (CNS) is exposed to a complex array of environmental stressors. However, the effects of long-duration spaceflight on the CNS and the resulting impact to crew health and operational performance remain largely unknown. In this review, we summarize the current knowledge regarding spaceflight-associated changes to the brain as measured by magnetic resonance imaging, particularly as they relate to mission duration. Numerous studies have reported macrostructural changes to the brain after spaceflight, including alterations in brain position, tissue volumes and cerebrospinal fluid distribution and dynamics. Changes in brain tissue microstructure and connectivity were also described, involving regions related to vestibular, cerebellar, visual, motor, somatosensory and cognitive function. Several alterations were also associated with exposure to analogs of spaceflight, providing evidence that brain changes likely result from cumulative exposure to multiple independent environmental stressors. Whereas several studies noted that changes to the brain become more pronounced with increasing mission duration, it remains unclear if these changes represent compensatory phenomena or maladaptive dysregulations. Future work is needed to understand how spaceflight-associated changes to the brain affect crew health and performance, with the goal of developing comprehensive monitoring and countermeasure strategies for future long-duration space exploration.

在太空飞行期间，中枢神经系统 (CNS) 暴露于一系列复杂的环境压力源下。然而，长时间太空飞行对中枢神经系统的影响以及由此对机组人员健康和操作绩效产生的影响仍然很大程度上未知。在这篇综述中，我们总结了通过磁共振成像测量的与航天相关的大脑变化的当前知识，特别是与任务持续时间相关的知识。许多研究报告了太空飞行后大脑宏观结构的变化，包括大脑位置、组织体积以及脑脊液分布和动力学的变化。还描述了脑组织微观结构和连接性的变化，涉及与前庭、小脑、视觉、运动、体感和认知功能相关的区域。一些变化也与暴露于类似的太空飞行有关，这提供了证据表明大脑的变化可能是由于累积暴露于多种独立的环境压力源而引起的。尽管一些研究指出，随着任务持续时间的增加，大脑的变化变得更加明显，但目前尚不清楚这些变化是否代表代偿现象或适应不良。未来的工作需要了解与航天相关的大脑变化如何影响机组人员的健康和表现，目标是为未来的长期太空探索制定全面的监测和对策策略。