Key Laboratory of Brain, Cognition and Education Sciences (South China Normal University), Ministry of Education, Guangzhou, 510631, China.
School of Psychology, South China Normal University, Guangzhou, 510631, China.
Brain Topogr. 2020 Nov;33(6):720-732. doi: 10.1007/s10548-020-00792-3. Epub 2020 Aug 17.
The default mode network (DMN) reflects spontaneous activity in the resting human brain. Previous studies examined the difference in static functional connectivity (sFC) of the DMN between eyes-closed (EC) and eyes-open (EO) using the resting-state functional magnetic resonance imaging (rs-fMRI) data. However, it remains unclear about the difference in dynamic FC (dFC) of the DMN between EC and EO. To this end, we acquired rs-fMRI data from 19 subjects in two different statues (EC and EO) and selected a seed region-of-interest (ROI) at the posterior cingulate cortex (PCC) to generate the sFC map. We identified the DMN consisting of ten clusters that were significantly correlated with the PCC. By using a sliding-window approach, we analyzed the dFC of the DMN. Then, the Newman's modularity algorithm was applied to identify dFC states based on nodal total connectivity strength in each sliding-window. In addition, graph-theory based network analysis was applied to detect dynamic topological properties of the DMN. We identified three group-level dFC states (State1, 2 and 3) that reflects the strength of dFC within the DMN between EC and EO in different time. The following results were reached: (1) no significant difference in sFC between EC and EO, (2) dFC was lower in State2 but higher in State3 in EC than in EO, (3) lower clustering coefficient, local efficiency, and global efficiency, but higher characteristic path length in State2 in EC than in EO, and (4) lower nodal strength in the precuneus (PCUN), PCC, angular gyrus (ANG), middle temporal gyrus (MTG) and medial prefrontal cortex (MPFC) in State3 in EC. These results suggested different resting statuses, EC and EO, may induce different time-varying neural activity in the DMN.
默认模式网络（DMN）反映了人类大脑在静息状态下的自发性活动。先前的研究使用静息态功能磁共振成像（rs-fMRI）数据，考察了闭眼（EC）和睁眼（EO）状态下 DMN 的静息态功能连接（sFC）差异。然而，EC 和 EO 状态下 DMN 的动态功能连接（dFC）差异仍不清楚。为此，我们在两种不同状态（EC 和 EO）下从 19 名被试中获取 rs-fMRI 数据，并选择后扣带皮层（PCC）的种子区域作为兴趣区（ROI），以生成 sFC 图。我们确定了由十个与 PCC 显著相关的聚类组成的 DMN。通过使用滑动窗口方法，我们分析了 DMN 的 dFC。然后，基于每个滑动窗口中节点总连接强度，应用 Newman 模块化算法识别 dFC 状态。此外，基于图论的网络分析用于检测 DMN 的动态拓扑特性。我们识别了三个组水平的 dFC 状态（State1、2 和 3），它们反映了 EC 和 EO 之间 DMN 内 dFC 的强度在不同时间的变化。得到的结果如下：（1）EC 和 EO 之间的 sFC 没有显著差异；（2）EC 中 State2 的 dFC 较低，State3 的 dFC 较高；（3）EC 中 State2 的聚类系数、局部效率和全局效率较低，特征路径长度较高；（4）EC 中 State3 的楔前叶（PCUN）、PCC、角回（ANG）、颞中回（MTG）和内侧前额叶皮层（MPFC）的节点强度较低。这些结果表明，不同的静息状态，EC 和 EO，可能会在 DMN 中引起不同的时变神经活动。
