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目的:通过n-back语义工作记忆任务的功能磁共振成像(fMRI)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。
OBJECTIVE: To investigate the neuropathological mechanism of semantic working memory impairment in patients with liver cirrhosis by functional magnetic resonance imaging (fMRI) of n-back semantic working memory task. Methods: The fMRI study of n-back semantic working memory was performed in 10 patients with mild hepatic encephalopathy (MHE), 14 patients with cirrhosis (non-HE) and 16 healthy controls (control group). The n-back experiment uses a chunk design with a 0-back control status and 1-back and 2-back tasks. Using MATLAB SPM8 software on the data processing analysis. Single-sample t test was used to analyze the activation of brain in three groups of subjects under two task states. One-way analysis of variance (ANOVA) was used to observe the differences in brain activation between the two task states (1 and 2-back) Pearson correlation analysis was used to analyze the correlation between task activation correct rate and response time in working memory task. RESULTS: In the n-back task, all three subjects demonstrated activation of the frontal lobe brain network, including bilateral prefrontal lobes, bilateral parietal lobes, bilateral anterior motor areas, and ancillary motor areas. Under the 1-back task, non-HE group and MHE group mainly showed an increase of brain activation in working memory part. In 2-back task, non-HE group and MHE group showed decreased working memory-related brain activation . Left frontal and mid-stroke activation in patients with cirrhosis is closely related to the correct rate of 2-back mission. CONCLUSIONS: There is semantic damage in brain regions associated with cirrhosis in patients with cirrhosis. 1-back task mainly for the compensation of the brain area, but MHE rather than purely compensatory ability to reduce cirrhosis; 2-back task beyond the compensatory limit of difficulty, mainly decreased activation, and MHE damage more significantly than simple cirrhosis .