遗忘型轻度认知障碍患者默认网络改变:基于后扣带回的脑连接研究

目的 探讨遗忘型轻度认知障碍(aMCI)患者后扣带回(PCC)功能连接的变化。 方法 选取性别、年龄和教育程度相匹配的18例aMCI患者(aMCI组)和20名健康老年人(健康老年组)进行GRE-EPI序列的静息状态fMRI检查,以PCC作为种子点,与全脑其他区域进行基于体素的时间序列相关分析。 结果 aMCI组与PCC有显著连接的脑区包括双侧背外侧前额叶(DLPFC)、左侧内侧前额叶(MPFC)及左侧前扣带回(ACC)、双侧顶下小叶(IPL)、双侧颞中回和双侧楔前叶。健康老年组与PCC有显著连接的脑区包括双侧DLPFC、右侧MPFC及ACC、双侧IPL、双侧颞中回、双侧颞下回和双侧楔前叶。健康老年组较aMCI组在右侧额上回、额中回、额下回的盖部及三角部、MPFC及ACC、颞中回及左侧楔前叶连接增强;aMCI组多个脑区功能连接较健康老年组增强,主要包括左侧半球的扣带回中部、顶上小叶(SPL)、IPL、颞中回及右侧IPL。 结论 PCC是aMCI患者脑代谢最先降低的区域,aMCI的PCC与多个功能区的连接破坏是其情节记忆功能减退的生物学基础,而其连接增强提示功能代偿可能。

Changes of default mode network in amnestic mild cognitive impairment: Evidence from PCC functional connectivity

Objective To investigate the changes of posterior cingulate cortex (PCC) functional connectivity in amnestic mild cognitive impairment (aMCI). Methods Eighteen patients of aMCI (aMCI group) and 20 healthy elderly (healthy elderly group) were enrolled, and the age, education level and sex were matched between two groups. Resting state fMRI was performed on all the subjects with GRE-EPI. Correlation analysis between PCC and all the other voxels in the brain was performed with a voxel-wise manner. Results In aMCI group, bilateral dorsolateral prefrontal cortex (DLPFC), left medial prefrontal cortex (MPFC) and anterior cingulate cortex (ACC), bilateral inferior parietal lobule (IPL), bilateral middle temporal gyrus and precuneus showed significant functional connectivity to PCC. In healthy elderly group, areas showing significant functional connectivity to PCC included DLPFC, right MPFC and ACC, bilateral IPL, bilateral middle and inferior temporal gyrus, as well as bilateral precuneus. Multiple areas including superior/middle frontal gyrus, inferior frontal gyrus (p.Opercularis/p.Triangularis), MPFC/ACC, middle temporal gyrus in right hemisphere, as well as left precuneus, showed increased functional connectivity to PCC in healthy elderly group compared to aMCI group. Meanwhile, a series of brain areas, including middle cingulate cortex, superior parietal lobule (SPL), IPL, middle temporal gyrus in the left hemisphere, as well as right SPL, showed increased functional connectivity to PCC in aMCI group compared to healthy elderly group. Conclusion Impaired functional connectivity between PCC and a distributed set of brain areas are considered as the biological basis of hypo-activity in episodic memory in aMCI patients. Increased PCC functional connectivity may be indicative of functional compensation.