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目的采用行为学和血氧依赖水平功能磁共振成像(BOLD-fMRI)方法探讨轻微型肝性脑病患者空间工作记忆损伤的脑神经机制。资料与方法从符合肝硬化诊断的40例患者中筛选出轻微型肝性脑病患者12例与正常对照者12名进行n-back任务负载下的脑fMRI扫描,以AFNI软件对fMRI数据进行定位定量分析。结果 (1)轻微型肝性脑病患者在三种任务负载下的正确率明显低于正常对照组,平均反应时间亦明显延长,两组差异具有显著性(P<0.001)。(2)fMRI结果发现,在n-back任务负载下,两组被试共同激活的脑区包括双侧前额叶(PFC),前运动区(PreMA),辅助运动区(SMA)及双侧顶叶(PA),且以右侧大脑半球优势为主。对这些感兴趣区进行定量分析发现,正常对照组这些脑区均表现出了和记忆负载相关的负载效应,而轻微型肝性脑病组只在双侧前运动区及双侧顶叶发现了这种负载效应。组间比较发现,在n-back任务负载下轻微型肝性脑病患者大部分工作记忆相关脑区的激活强度均比正常对照组小。结论轻微型肝性脑病患者存在空间工作记忆损伤,双侧前额叶、前运动区、辅助运动区及双侧顶叶功能减弱是空间工作记忆损伤的机制之一。
Objective To investigate the neurological mechanism of spatial working memory impairment in patients with mild hepatic encephalopathy using behavioral and oximetry-based functional magnetic resonance imaging (BOLD-fMRI). Materials and Methods 12 patients with mild hepatic encephalopathy and 12 normal controls were screened out from 40 patients with cirrhosis for brain fMRI under n-back task load. The fMRI data were localized by AFNI software analysis. Results (1) The correct rate of patients with mild hepatic encephalopathy under three kinds of task load was significantly lower than that of the normal control group, the average reaction time was also significantly prolonged, the difference between the two groups was significant (P <0.001). (2) The results of fMRI showed that brain regions co-activated by n-back task load included bilateral prefrontal cortex (PFC), anterior motor zone (PreMA), ancillary motor zone (SMA) Leaves (PA), dominated by the right hemisphere. Quantitative analysis of these regions of interest revealed that these brain regions in the normal control group showed a load effect associated with memory load whereas the mild-to-severe hepatic encephalopathy group found this only in the bilateral anterior motor region and bilateral parietal lobe Load effect. Comparisons between groups showed that the activation intensity of most working memory-related brain regions in patients with mild hepatic encephalopathy under n-back task load was smaller than that of the normal control group. Conclusions There is spatial working memory impairment in patients with mild hepatic encephalopathy. One of the mechanisms of spatial working memory impairment is bilateral prefrontal gyrus, anterior motor zone, ancillary motor zone and bilateral parietal lobe dysfunction.