Developing Brain Institute, Children's National, 111 Michigan Ave NW, Washington DC 20010.
Division of Diagnostic Imaging and Radiology, 111 Michigan Ave NW, Washington DC 20010.
Cereb Cortex. 2021 May 10;31(6):3034-3046. doi: 10.1093/cercor/bhaa410.
Recent advances in brain imaging have enabled non-invasive in vivo assessment of the fetal brain. Characterizing brain development in healthy fetuses provides baseline measures for identifying deviations in brain function in high-risk clinical groups. We examined 110 resting state MRI data sets from fetuses at 19 to 40 weeks' gestation. Using graph-theoretic techniques, we characterized global organizational features of the fetal functional connectome and their prenatal trajectories. Topological features related to network integration (i.e., global efficiency) and segregation (i.e., clustering) were assessed. Fetal networks exhibited small-world topology, showing high clustering and short average path length relative to reference networks. Likewise, fetal networks' quantitative small world indices met criteria for small-worldness (σ > 1, ω = [-0.5 0.5]). Along with this, fetal networks demonstrated global and local efficiency, economy, and modularity. A right-tailed degree distribution, suggesting the presence of central areas that are more highly connected to other regions, was also observed. Metrics, however, were not static during gestation; measures associated with segregation-local efficiency and modularity-decreased with advancing gestational age. Altogether, these suggest that the neural circuitry underpinning the brain's ability to segregate and integrate information exists as early as the late 2nd trimester of pregnancy and reorganizes during the prenatal period. Significance statement. Mounting evidence for the fetal origins of some neurodevelopmental disorders underscores the importance of identifying features of healthy fetal brain functional development. Alterations in prenatal brain connectomics may serve as early markers for identifying fetal-onset neurodevelopmental disorders, which in turn provide improved surveillance of at-risk fetuses and support the initiation of early interventions.
近年来,脑成像技术的进步使得对胎儿大脑进行非侵入性的体内评估成为可能。对健康胎儿大脑发育进行特征描述为识别高危临床群体中大脑功能偏差提供了基线测量值。我们检查了 19 至 40 孕周胎儿的 110 个静息状态 MRI 数据集。使用图论技术,我们描述了胎儿功能连接组的全局组织特征及其产前轨迹。评估了与网络集成(即全局效率)和隔离(即聚类)相关的拓扑特征。胎儿网络表现出小世界拓扑结构,与参考网络相比,聚类度高且平均路径长度短。同样,胎儿网络的定量小世界指数符合小世界的标准(σ>1,ω= [-0.5 0.5])。此外,胎儿网络还表现出全局和局部效率、经济性和模块性。还观察到了右偏度分布,表明存在与其他区域高度连接的中央区域。然而,指标在妊娠期间并非静态不变;与隔离有关的指标——局部效率和模块性——随着胎龄的增加而降低。总的来说,这些结果表明,支持大脑分离和整合信息能力的神经回路早在妊娠中期就存在,并在产前阶段重新组织。研究意义。越来越多的证据表明,一些神经发育障碍与胎儿起源有关,这突显了识别健康胎儿大脑功能发育特征的重要性。产前脑连接组学的改变可能成为识别胎儿神经发育障碍的早期标志物,从而更好地监测高危胎儿,并支持早期干预的开展。