Dajani Dina R, Uddin Lucina Q
From Department of Psychology, University of Miami, Coral Gables, FL.
Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL.
Autism Res. 2016 Jan;9(1):43-54. doi: 10.1002/aur.1494. Epub 2015 Jun 8.
There is a general consensus that autism spectrum disorder (ASD) is accompanied by alterations in brain connectivity. Much of the neuroimaging work has focused on assessing long-range connectivity disruptions in ASD. However, evidence from both animal models and postmortem examination of the human brain suggests that local connections may also be disrupted in individuals with the disorder. Here, we investigated how regional homogeneity (ReHo), a measure of similarity of a voxel's timeseries to its nearest neighbors, varies across age in individuals with ASD and typically developing (TD) individuals using a cross-sectional design. Resting-state fMRI data obtained from a publicly available database were analyzed to determine group differences in ReHo between three age cohorts: children, adolescents, and adults. In typical development, ReHo across the entire brain was higher in children than in adolescents and adults. In contrast, children with ASD exhibited marginally lower ReHo than TD children, while adolescents and adults with ASD exhibited similar levels of local connectivity as age-matched neurotypical individuals. During all developmental stages, individuals with ASD exhibited lower local connectivity in sensory processing brain regions and higher local connectivity in complex information processing regions. Further, higher local connectivity in ASD corresponded to more severe ASD symptomatology. These results demonstrate that local connectivity is disrupted in ASD across development, with the most pronounced differences occurring in childhood. Developmental changes in ReHo do not mirror findings from fMRI studies of long-range connectivity in ASD, pointing to a need for more nuanced accounts of brain connectivity alterations in the disorder.
人们普遍认为，自闭症谱系障碍（ASD）伴有大脑连接性的改变。许多神经影像学研究都集中在评估ASD中的长程连接中断。然而，来自动物模型和人类大脑尸检的证据表明，患有该疾病的个体的局部连接也可能受到破坏。在这里，我们采用横断面设计，研究了体素时间序列与其最近邻体素的相似性度量——局部一致性（ReHo）在ASD个体和正常发育（TD）个体中随年龄的变化情况。我们分析了从一个公开可用数据库中获得的静息态功能磁共振成像（fMRI）数据，以确定三个年龄组（儿童、青少年和成年人）之间ReHo的组间差异。在正常发育过程中，全脑的ReHo在儿童中高于青少年和成年人。相比之下，ASD儿童的ReHo略低于TD儿童，而ASD青少年和成年人表现出与年龄匹配的神经典型个体相似的局部连接水平。在所有发育阶段，ASD个体在感觉处理脑区表现出较低的局部连接，而在复杂信息处理区域表现出较高的局部连接。此外，ASD中较高的局部连接与更严重的ASD症状相对应。这些结果表明，ASD在整个发育过程中局部连接受到破坏，最明显的差异出现在儿童期。ReHo的发育变化与ASD长程连接的fMRI研究结果不一致，这表明需要对该疾病中大脑连接改变进行更细致入微的描述。
