Wang Pengyun, Li Rui, Yu Jing, Huang Zirui, Li Juan
Key Laboratory of Mental Health, Center on Aging Psychology, Institute of Psychology, Chinese Academy of Sciences Beijing, China.
Faculty of Psychology, Southwest University Chongqing, China.
Front Aging Neurosci. 2016 Mar 24;8:60. doi: 10.3389/fnagi.2016.00060. eCollection 2016.
Several studies have reported working memory deficits in patients with mild cognitive impairment (MCI). However, previous studies investigating the neural mechanisms of MCI have primarily focused on brain activity alterations during working memory tasks. No study to date has compared brain network alterations in the working memory state between MCI patients and normal control (NC) subjects. Therefore, using the index of regional homogeneity (ReHo), we explored brain network impairments in MCI patients during a working memory task relative to the resting state, and identified frequency-dependent effects in separate frequency bands.Our results indicate that, in MCI patients, ReHo is altered in the posterior cingulate cortex (PCC) in the slow-3 band (0.073-0.198 Hz), and in the bottom of the right occipital lobe and part of the right cerebellum, the right thalamus, a diffusing region in the bilateral prefrontal cortex (PFC), the left and right parietal-occipital regions, and the right angular gyrus in the slow-5 band (0.01-0.027 Hz). Furthermore, in NCs, the value of ReHo in clusters belonging to the default mode network (DMN) decreased, while the value of ReHo in clusters belonging to the attentional network increased during the task state. However, this pattern was reversed in MCI patients, and was associated with decreased working memory performance. In addition, we identified altered functional connectivity of the abovementioned regions with other parts of the brain in MCI patients. This is the first study to compare frequency-dependent alterations of ReHo in MCI patients between resting and working memory states. The results provide a new perspective regarding the neural mechanisms of working memory deficits in MCI patients, and extend our knowledge of altered brain patterns in resting and task-evoked states.
多项研究报告了轻度认知障碍（MCI）患者存在工作记忆缺陷。然而，以往研究MCI神经机制主要聚焦于工作记忆任务期间的大脑活动变化。迄今为止，尚无研究比较MCI患者与正常对照（NC）受试者在工作记忆状态下的脑网络变化。因此，我们使用局部一致性（ReHo）指标，探讨了MCI患者在工作记忆任务期间相对于静息状态的脑网络损伤情况，并确定了不同频段的频率依赖性效应。我们的结果表明，在MCI患者中，慢3频段（0.073 - 0.198 Hz）时后扣带回皮质（PCC）的ReHo发生改变，在慢5频段（0.01 - 0.027 Hz）时右枕叶底部、右小脑部分区域、右丘脑、双侧前额叶皮质（PFC）的一个弥散区域、左右顶枕区域以及右角回的ReHo发生改变。此外，在NC受试者中，属于默认模式网络（DMN）的簇在任务状态下ReHo值降低，而属于注意力网络的簇在任务状态下ReHo值增加。然而，在MCI患者中这种模式相反，且与工作记忆表现下降相关。此外，我们还发现MCI患者上述区域与大脑其他部分的功能连接发生改变。这是第一项比较MCI患者在静息和工作记忆状态下ReHo频率依赖性变化的研究。研究结果为MCI患者工作记忆缺陷的神经机制提供了新的视角，并扩展了我们对静息和任务诱发状态下大脑模式改变的认识。
