Yao Shuxia, Becker Benjamin, Kendrick Keith M
The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Laboratory for NeuroInformation, Center for Information in Medicine, University of Electronic Science and Technology of China, Chengdu, China.
Front Psychiatry. 2021 Mar 4;12:629870. doi: 10.3389/fpsyt.2021.629870. eCollection 2021.
Autism spectrum disorder (ASD) is an early onset developmental disorder which persists throughout life and is increasing in prevalence over the last few decades. Given its early onset and variable cognitive and emotional functional impairments, it is generally challenging to assess ASD individuals using task-based behavioral and functional MRI paradigms. Consequently, resting state functional MRI (rs-fMRI) has become a key approach for examining ASD-associated neural alterations and revealed functional alterations in large-scale brain networks relative to typically developing (TD) individuals, particularly those involved in social-cognitive and affective processes. Recent progress suggests that alterations in inter-hemispheric resting state functional connectivity (rsFC) between regions in the 2 brain hemispheres, particularly homotopic ones, may be of great importance. Here we have reviewed neuroimaging studies examining inter-hemispheric rsFC abnormities in ASD and its associations with symptom severity. As an index of inter-hemispheric functional connectivity, we have additionally reviewed previous studies on corpus callosum (CC) volumetric and fiber changes in ASD. There are converging findings on reduced inter-hemispheric (including homotopic) rsFC in large-scale brain networks particularly in posterior hubs of the default mode network, reduced volumes in the anterior and posterior CC, and on decreased FA and increased MD or RD across CC subregions. Associations between the strength of inter-hemispheric rsFC and social impairments in ASD together with their classification performance in distinguishing ASD subjects from TD controls across ages suggest that the strength of inter-hemispheric rsFC may be a more promising biomarker for assisting in ASD diagnosis than abnormalities in either brain wide rsFC or brain structure.
自闭症谱系障碍（ASD）是一种起病早且会持续终生的发育障碍，在过去几十年中其患病率呈上升趋势。鉴于其起病早以及认知和情感功能损害的多样性，使用基于任务的行为和功能磁共振成像范式来评估ASD个体通常具有挑战性。因此，静息态功能磁共振成像（rs-fMRI）已成为研究与ASD相关的神经改变的关键方法，并揭示了相对于正常发育（TD）个体而言，大规模脑网络中的功能改变，特别是那些涉及社会认知和情感过程的脑网络。最近的研究进展表明，两个脑半球区域之间，尤其是同位区域之间的半球间静息态功能连接（rsFC）改变可能具有重要意义。在此，我们回顾了研究ASD半球间rsFC异常及其与症状严重程度关联的神经影像学研究。作为半球间功能连接的一个指标，我们还回顾了先前关于ASD胼胝体（CC）体积和纤维变化的研究。目前有一些一致的研究结果，包括大规模脑网络中半球间（包括同位区域）rsFC降低，尤其是在默认模式网络的后部枢纽区域；CC的前部和后部体积减小；以及CC各亚区域的分数各向异性（FA）降低、平均弥散率（MD）或径向弥散率（RD）增加。ASD中半球间rsFC强度与社交障碍之间的关联，以及它们在区分不同年龄段ASD受试者与TD对照中的分类表现表明，半球间rsFC强度可能比全脑rsFC或脑结构异常更有希望成为辅助ASD诊断的生物标志物。
