模拟失重对人脑工作记忆的影响:系列功能磁共振成像研究

目的 采用功能性磁共振技术研究微重力环境对工作记忆的影响. 方法 9名健康男性青年头低位卧床4周.卧床前、卧床1周时和卧床4周后各对其进行1次倒数2项工作记忆任务的功能磁共振成像扫描. 结果 模拟失重前,工作记忆任务激活的脑区有双侧额叶(BA46/9、47、6)、前扣带回(BA32)、双侧顶叶(BA7)、双侧枕叶(19/18)和左侧丘脑.模拟失重1周时,激活脑区的范围和信号强度变化显著.模拟失重4周后,激活脑区与卧床前趋于相似. 结论 ①模拟失重状态时,人脑工作记忆功能状态有明显的变化,主要表现为功能脑区激活范围和部位的变化;②模拟失重环境对工作记忆信息的被动贮存影响不大,但对信息的主动复述维持及中央执行系统的信息操作功能有明显、可逆的影响;③失重1周时,人脑激活区变化显著.失重4周时,人脑已经开始逐步适应,但未正常化.

Effects of simulated weightlessness on working memory of human brain: a series of studies of functional magnetic resonance imaging

Objective To investigate the effect of simulated weightlessness on human working memory by using functional magnetic resonance imaging (fMRI). Methods Nine young male volunteers underwent - 6° head-down bed rest (HDBR) for four weeks. Series fMRI scans were performed on them one day before experiment, one week and four weeks after HDBR with block designed 2-back working memory task. Results The engagement of working memory before HDBR produced significant activation in the prefrontal cortex (bi-lateralized BA46/9, left> right; bi- lateralized BA47; right BA6), anterior cingulated gyrus(BA32), bi-lateralized posterior parietal lobe (BAT,left>right), bi-lateralized occipital lobe (BA19/18) and left thalamus. Compared with those before HDBR, the engagement of working memory one week after HDBR brain activation size and signal magnitude changed significantly. However, compared with those before HDBR, there was unsignificant change four weeks after HDBR. Conclusions ①The brain activation size and location of working memory would change after HDBR. ②HDBR may change the active maintenance and manipulation of information but not the passive storage of information of human brain. ③And the change can be very salient one week after HDBR. However, human brain may adapt to HDBR after four weeks.