Institute of Brain and Psychological Science, Sichuan Normal University, Chengdu, Sichuan, China.
Faculty of Psychology, Southwest University, Chongqing, China.
Cereb Cortex. 2023 Feb 7;33(4):969-982. doi: 10.1093/cercor/bhac115.
As a major contributor to the development of depression, rumination has proven linked with aberrant default-mode network (DMN) activity. However, it remains unclear how the spontaneous spatial and temporal activity of DMN underlie the association between rumination and depression. To illustrate this issue, behavioral measures and resting-state functional magnetic resonance images were connected in 2 independent samples (NSample1 = 100, NSample2 = 95). Fractional amplitude of low-frequency fluctuations (fALFF) and regional homogeneity (ReHo) were used to assess spatial characteristic patterns, while voxel-wise functional concordance (across time windows) (VC) and Hurst exponent (HE) were used to assess temporal dynamic patterns of brain activity. Results from both samples consistently show that temporal dynamics but not spatial patterns of DMN are associated with rumination. Specifically, rumination is positively correlated with HE and VC (but not fALFF and ReHo) values, reflecting more consistent and regular temporal dynamic patterns in DMN. Moreover, subregion analyses indicate that temporal dynamics of the ventromedial prefrontal cortex (VMPFC) reliably predict rumination scores. Furthermore, mediation analyses show that HE and VC of VMPFC mediate the association between rumination and depression. These findings shed light on neural mechanisms of individual differences in rumination and corresponding risk for depression.
作为导致抑郁的主要因素之一，反刍已被证明与异常的默认模式网络（DMN）活动有关。然而，DMN 的自发空间和时间活动如何构成反刍与抑郁之间的关联仍不清楚。为了说明这个问题，在两个独立的样本中（样本 1=100，样本 2=95）将行为测量和静息态功能磁共振成像连接起来。分数低频波动幅度（fALFF）和局部一致性（ReHo）用于评估空间特征模式，而体素间功能一致性（跨越时间窗口）（VC）和赫斯特指数（HE）用于评估大脑活动的时间动态模式。两个样本的结果都一致表明，DMN 的时间动态而非空间模式与反刍有关。具体来说，反刍与 HE 和 VC（而不是 fALFF 和 ReHo）值呈正相关，反映了 DMN 中更一致和规则的时间动态模式。此外，亚区分析表明，腹内侧前额叶皮层（VMPFC）的时间动态可靠地预测反刍评分。此外，中介分析表明，VMPFC 的 HE 和 VC 介导了反刍与抑郁之间的关联。这些发现为反刍和相应抑郁风险的个体差异的神经机制提供了线索。
