State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China.
State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China; School of Systems Science, Beijing Normal University, Beijing, China.
Neuroimage. 2021 Apr 1;229:117761. doi: 10.1016/j.neuroimage.2021.117761. Epub 2021 Jan 14.
The left and right hemispheres of the human brain are two connected but relatively independent functional modules; they show multidimensional asymmetries ranging from particular local brain unit properties to entire hemispheric connectome topology. To date, however, it remains largely unknown whether and how hemispheric functional hierarchical structures differ between hemispheres. In the present study, we adopted a newly developed resting-state (rs) functional connectivity (FC)-based gradient approach to evaluate hemispheric functional hierarchical structures and their asymmetries in right-handed healthy young adults. Our results showed an overall mirrored principal functional gradient between hemispheres, with the sensory cortex and the default-mode network (DMN) anchored at the two opposite ends of the gradient. Interestingly, the left hemisphere showed a significantly larger full range of the principal gradient in both males and females, with males exhibiting greater leftward asymmetry. Similarly, the principal gradient component scores of two regions around the middle temporal gyrus and posterior orbitofrontal cortex exhibited similar hemisphere × sex interaction effects: a greater degree of leftward asymmetry in males than in females. Moreover, we observed significant main hemisphere and sex effects in distributed regions across the entire hemisphere. All these results are reproducible and robust between test-retest rs-fMRI sessions. Our findings provide evidence of functional gradients that enhance the present understanding of human brain asymmetries in functional organization and highlight the impact of sex on hemispheric functional gradients and their asymmetries.
人脑的左右半球是两个相互连接但相对独立的功能模块；它们表现出从特定的局部脑单元特性到整个半球连接组拓扑的多维不对称性。然而，迄今为止，人们仍然很大程度上不知道左右半球的半球功能层次结构是否存在差异，以及如何存在差异。在本研究中，我们采用了一种新开发的基于静息态（rs）功能连接（FC）的梯度方法来评估右利手健康年轻成年人的半球功能层次结构及其不对称性。我们的结果显示了半球之间整体镜像的主要功能梯度，感觉皮层和默认模式网络（DMN）位于梯度的两个相反端。有趣的是，男性和女性的左半球都表现出了更大的全范围主梯度，男性表现出了更大的左偏性。同样，围绕颞中回和后眶额皮层的两个区域的主梯度分量得分也表现出类似的半球×性别相互作用效应：男性的左偏性大于女性。此外，我们在整个半球的分布式区域观察到了显著的主要半球和性别效应。所有这些结果在 rs-fMRI 测试-重测会话之间都是可重复和稳健的。我们的研究结果提供了功能梯度的证据，增强了对人类大脑功能组织中不对称性的理解，并强调了性别的影响对半球功能梯度及其不对称性的影响。
