Chen Xiao, Chen Ning-Xuan, Shen Yang-Qian, Li Hui-Xian, Li Le, Lu Bin, Zhu Zhi-Chen, Fan Zhen, Yan Chao-Gan
CAS Key Laboratory of Behavioral Science, Institute of Psychology, Beijing 100101, China; International Big-Data Center for Depression Research, Institute of Psychology, Chinese Academy of Sciences, Beijing, 100101, China; Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing, 100101, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, 100049, China.
Graduate School of Education, Fordham University, New York, NY, 10023, United States.
Neuroimage. 2020 Nov 1;221:117185. doi: 10.1016/j.neuroimage.2020.117185. Epub 2020 Jul 22.
Rumination is a repetitive self-referential thinking style that is often interpreted as an expression of abnormalities of the default mode network (DMN) observed during "resting-state" in major depressive disorder (MDD). Recent evidence has demonstrated that the DMN is not unitary but can be further divided into 3 functionally heterogenous subsystems, although the subsystem mechanistically underlying rumination remains unclear. Due to the unconstrained and indirect correlational nature of previous resting-state fMRI studies on rumination's network underpinnings, a paradigm allowing direct investigation of network interactions during active rumination is needed. Here, with a modified continuous state-like paradigm, we induced healthy participants to ruminate or imagine objective scenarios (distraction, as a control condition) on 3 different MRI scanners. We compared functional connectivities (FC) of the DMN and its 3 subsystems between rumination and distraction states. Results yielded a highly reproducible and dissociated pattern. During rumination, within-DMN FC was generally decreased as compared to the distraction state. At the subsystem level, we found increased FC between the core and medial temporal lobe (MTL) subsystem as well as decreased FC between the core and dorsal medial prefrontal cortex (DMPFC) subsystem and within the MTL subsystem. Finally, subjects' behavioral measures of rumination and brooding were negatively correlated with FC between the core and DMPFC subsystems. These results suggest active rumination involves enhanced constraint by the core subsystem on the MTL subsystem and decreased coupling between the core and DMPFC subsystem, allowing for more information exchange among those involved DMN components. Furthermore, the reproducibility of our findings provides a rigorous evaluation of their validity and significance.
反刍是一种重复性的自我参照思维方式，通常被解释为在重度抑郁症（MDD）“静息状态”下观察到的默认模式网络（DMN）异常的一种表现。最近的证据表明，DMN并非单一的，而是可以进一步分为3个功能异质的子系统，尽管反刍背后的子系统机制仍不清楚。由于先前关于反刍网络基础的静息态功能磁共振成像（fMRI）研究具有无约束和间接相关的性质，因此需要一种能够直接研究主动反刍过程中网络相互作用的范式。在此，我们采用一种改良的连续状态样范式，在3台不同的磁共振成像（MRI）扫描仪上诱导健康参与者进行反刍或想象客观场景（分心，作为对照条件）。我们比较了反刍状态和分心状态下DMN及其3个子系统的功能连接性（FC）。结果产生了一种高度可重复且分离的模式。在反刍过程中，与分心状态相比，DMN内的FC普遍降低。在子系统层面，我们发现核心与内侧颞叶（MTL）子系统之间的FC增加，以及核心与背内侧前额叶皮质（DMPFC）子系统之间和MTL子系统内的FC降低。最后，受试者反刍和沉思的行为测量与核心和DMPFC子系统之间的FC呈负相关。这些结果表明，主动反刍涉及核心子系统对MTL子系统的约束增强，以及核心与DMPFC子系统之间的耦合减少，从而允许参与DMN的各组件之间进行更多信息交换。此外，我们研究结果的可重复性为其有效性和重要性提供了严格的评估。
