College of Psychology and Sociology, Shenzhen University, Shenzhen 518060, China; Shenzhen Key Laboratory of Affective and Social Cognitive Science, Shenzhen University, Shenzhen 518060, China.
Department of Radiology, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou 100053, China.
J Affect Disord. 2018 Jul;234:297-304. doi: 10.1016/j.jad.2017.12.033. Epub 2017 Dec 28.
Major depressive disorder (MDD) is characterized by impairments in emotional and cognitive functions. Emerging studies have shown that cognition and emotion interact by reaching identical brain regions, and the insula is one such region with functional and structural heterogeneity. Although previous literatures have shown the role of insula in MDD，it remains unclear whether the insular subregions show differential change patterns in MDD.
Using the resting-state fMRI data in a group of 23 drug-free MDD patients and 34 healthy controls (HCs), we investigated whether the abnormal connectivity patterns of insular sub-regions or any behavioural correlates can be detected in MDD. Further hierarchical cluster analysis was used to identify the functional connectivity-clustering patterns of insular sub-regions.
Compared with HCs, the MDD exhibited higher connectivities between dorsal agranular insula and inferior parietal lobule and between ventral dysgranular and granular insula and thalamus/habehula, and lower connectivity of hypergranular insula to subgenual anterior cingulate cortex. Moreover, the three subregions with significant group differences were in three separate functional systems along anterior-to-posteior gradient. The anterior and middle insula showed positive correlation with depressive severity, while the posterior insular was to the contrary.
The small and unbalanced sample size, only included moderate and severe depression and the possible inter-individual differences may limit the interpretability.
These findings provided evidences for the MDD-related effects in functional connectivity patterns of insular subregions, and revealed that the subregions might be involved in different neural circuits associated with the contrary impacts on the depressive symptoms.
重度抑郁症（MDD）的特征是情绪和认知功能受损。新兴研究表明，认知和情绪通过到达相同的大脑区域相互作用，而脑岛就是这样一个具有功能和结构异质性的区域。尽管先前的文献已经表明脑岛在 MDD 中的作用，但尚不清楚 MDD 是否存在脑岛亚区的差异变化模式。
使用一组 23 名未服用药物的 MDD 患者和 34 名健康对照者（HCs）的静息状态 fMRI 数据，我们研究了 MDD 是否可以检测到脑岛亚区的异常连接模式或任何行为相关性。进一步的层次聚类分析用于识别脑岛亚区的功能连接聚类模式。
与 HCs 相比，MDD 患者的背侧无颗粒脑岛与下顶叶回之间以及腹侧颗粒和颗粒脑岛与丘脑/缰核之间的连接性更高，而前扣带回亚皮质的颗粒脑岛的连接性更低。此外，三组具有显著组间差异的脑区位于三个沿着前后梯度的不同功能系统中。前岛和中岛与抑郁严重程度呈正相关，而后岛则相反。
小样本量且不平衡、仅包括中度和重度抑郁症以及可能的个体间差异可能会限制其可解释性。
这些发现为 MDD 相关的脑岛亚区功能连接模式提供了证据，并表明这些亚区可能参与了不同的神经回路，对抑郁症状产生了相反的影响。
