航天医学与医学工程

目的 采用静息态功能磁共振成像技术结合低氧模拟实验，探究急性缺氧对战斗机飞行员脑功能及认知能力的影响。方法 筛选2022年6月至2023年10月于某单位疗养的健康战斗机飞行员60名，通过吸入氧浓度为11.1%的低氧混合气体模拟5 000 m高空环境，对比分析低氧暴露前后神经心理测评结果及脑功能影像数据。结果 神经心理测评显示，低氧暴露后飞行员空间旋转测验（P=0.01）与二维数字搜索测验（P<0.01）的单位时间正确率显著下降，表明其空间想象与信息加工能力受损，而其他认知维度（如空间定位、学习能力）未见明显变化。静息态功能磁共振成像分析结果表明，低氧暴露后飞行员双侧额上回局部一致性减弱，而初级视皮质（双侧矩状皮质）局部一致性值增强；全局功能连接密度（FCD）分析显示，默认网络核心脑区（双侧扣带回后部、楔前叶）的FCD值显著降低。相关性分析进一步表明，空间想象能力下降与楔前叶FCD值降低呈正相关（r=0.57,P<0.01），提示该脑区在空间认知中起关键作用。结论 低氧暴露通过削弱高级认知脑区的局部与全局连接，引发视觉相关脑区的代偿性增强，导致飞行员特定认知功能受损。研究结果为解析低氧暴露下飞行员行为异常的神经机制提供了影像学证据，对优化飞行训练、改进防护措施及保障航空安全具有重要意义。

Objective To investigate the effects of acute hypoxia on brain function and cognitive ability in fighter pilots using resting-state functional magnetic resonance imaging(rs-fMRI) combined with a simulated hypoxia experiment. Methods A total of 60 healthy fighter pilots undergoing recuperation at a designated unit from June 2022 to October 2023 were selected. Hypoxia at an altitude of 5 000 m was simulated by having the participants inhale a hypoxic gas mixture with an oxygen concentration of 11.1%. Neuropsychological assessment results and brain functional imaging data before and after hypoxia exposure were compared and analyzed. Results Neuropsychological tests showed that after hypoxia exposure, the pilots' accuracy per unit time in the Spatial Rotation Test(P=0.01) and the Two-Dimensional Digit Search Test(P<0.01) decreased significantly, indicating impaired spatial imagination and information-processing abilities. Other cognitive dimensions(such as spatial orientation and learning ability) showed no significant changes. Rs-fMRI analysis revealed that after hypoxia exposure, regional homogeneity(ReHo) decreased in the bilateral superior frontal gyri, while ReHo increased in the primary visual cortex(bilateral calcarine cortex). Global functional connectivity density(FCD) analysis showed that FCD values in core regions of the default mode network(bilateral posterior cingulate cortex and precuneus) decreased significantly. Correlation analysis further indicated that the decline in spatial imagination ability was positively correlated with reduced FCD in the precuneus(r=0.57, P<0.01), suggesting that this brain region plays a key role in spatial cognition. Conclusion Hypoxia exposure impairs specific cognitive functions in pilots by weakening local and global connectivity in higher-order cognitive brain areas while inducing compensatory enhancement in vision-related regions. These findings provide imaging evidence for understanding the neural mechanisms underlying behavioral abnormalities in pilots under hypoxic conditions, which has important implications for optimizing flight training, improving protective measures, and ensuring aviation safety.