肝硬化患者工作记忆任务的fMRI研究

目的：通过n-back语义工作记忆任务的功能磁共振成像（~MRI）技术探讨肝硬化患者语义工作记忆损伤的神经病理学机制。方法：对10例轻微肝性脑病（MHE组）、14例单纯肝硬化（non-HE组）患者及16例正常对照者（对照组）行n-back语义工作记忆任务的fMRI研究。n-back实验采用组块设计，对照状态为0-back，任务状态为1-back和2-back。采用基于MATLAB的SPM8软件对数据进行处理分析。采用单样本t检验分析三组受试者在两种任务状态下的大脑激活情况，采用单因素方差分析观察三组受试者两种任务状态（1和2-back）下脑区激活的差异，采用Pearson相关分析行工作记忆任务脑激活区与任务执行正确率及反应时间之间的相关性。结果：在n-back任务中，三组受试者均表现为额顶叶脑网络的激活，包括双侧前额叶、双侧顶叶、双侧前运动区以及辅助运动区。在1-back任务下，non-HE组及MHE组主要表现为工作记忆部分脑区激活的增加；在2-back任务下，non-HE组及MHE组表现为工作记忆相关脑区激活的减低。肝硬化患者左侧额中回激活与2-back任务执行正确率密切相关。结论：肝硬化患者存在语义工作记忆相关脑区的损害。1-back任务时主要表现为脑区的代偿，但MHE较单纯肝硬化代偿能力减低；2-back任务难度超出代偿限度，主要表现为激活下降，且MHE较单纯肝硬化损伤更明显。

The fMRI study of working memory in cirrhosis patients

Objective：To investigate the neuro-pathologic basis of working memory impairment in cirrhotic patients by using n-back functional MRI （fMRI）. Methods：Twenty four patients （mild hepatic encephalopathy, MHE= 10;non-hepatic encephalopathy,non-HE= 14） and sixteen healthy subjects as control group underwent functional MRI examination with n- back working memory task. Block design was used for n-back fMRI. Control block （0-back） and task blocks （1,2-back） ran alternately. The fMRI data were processed by SPM8 software based on MATLAB. single sample t-test was used to analyze the brain activation pattern of three groups under different tasks. The brain activation was compared with ANOVA tests a- mong MHE,non-HE and healthy control groups. Correlation analyses were performed to explore the relationships between brain activation and the accuracy and reaction time. Results： All the three groups showed activation of frontal-parietal net- works, including the prefrontal cortex, bilateral parietal lobe, bilateral premotor cortex and the supplementary motor area under the n back task. Under the 1-back task, the patients manifested as an increase in related brain activation. Under the 2-back task, the patients showed reduced brain activation. The left middle frontal gyrus of cirrhotic patients was closely re- lated to 2-back accuracy. Conclusion：The cirrhotic patients showed impaired semantic working memory related to brain re- gions. The patients mainly manifested as a compensatory mechanism under 1 back condition, but the compensation in MHE was weakened than non-HE. The 2-back condition was beyond the compensation limit, mainly manifested as a reduction of brain activation, and the impairment in MHE was more serious than that of non-HE.