Institute of Neuroradiology, University Hospital of Zurich, Zurich, Switzerland; Center of MR-Research, University Children's Hospital, Zurich, Switzerland.
Digital Signal Processing and System Theory, Technische Fakultät Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
Neuroimage. 2013 Nov 1;81:231-242. doi: 10.1016/j.neuroimage.2013.04.030. Epub 2013 May 1.
Several studies demonstrated that resting-state EEG power differs tremendously between school-aged children and adults. Low-frequency oscillations (delta and theta, <7 Hz) are dominant in children but become less prominent in the adult brain, where higher-frequency alpha oscillations (8-12 Hz) dominate the mature brain rhythm. However, this assessment of developmental effects with EEG power mapping is restricted to the scalp level and blind to the information flow between brain regions, thus limiting insights about brain development. In contrast dynamic source synchronization provides a tool to study inter-regional directionality on the cortical and sub-cortical source level. In this study we investigated functional and directed connectivities (information flow) with renormalized partial directed coherence during resting state EEG (eyes open and eyes closed) recordings in 17 school-aged children and 17 young adults. First, we found higher spectral mean source power in children relative to adults, irrespective of the examined frequency band and resting state. We further found that coherence values were stronger in adults compared to children in all frequency bands. The directed within-group coherence analysis indicated information flow from frontal to parietal sources in children, while information flow from parietal to frontal was observed in adults. In addition, significant thalamocortical connectivity was unidirectional (i.e., outflow to cortical regions) in adults, but bidirectional in children. Group comparison confirmed the results of the single subject analyses for both functional and directed connectivities. Our results suggest that both functional and directed connectivities are sensitive to brain maturation as the distribution and directionality of functional connections differ between the developing and adult brains.
几项研究表明，静息状态脑电图的功率在学龄儿童和成年人之间存在巨大差异。低频振荡（δ 和θ，<7 Hz）在儿童中占主导地位，但在成人大脑中变得不那么明显，成人大脑中以更高频的α振荡（8-12 Hz）为主导。然而，这种通过脑电图功率映射评估发育影响的方法仅限于头皮水平，无法了解大脑区域之间的信息流，因此限制了对大脑发育的深入了解。相比之下，动态源同步提供了一种在皮质和皮质下源水平上研究区域间方向性的工具。在这项研究中，我们在 17 名学龄儿童和 17 名年轻成年人的静息状态脑电图（睁眼和闭眼）记录中，使用重归一化偏导相干性研究了功能和有向连通性（信息流）。首先，我们发现儿童的频谱平均源功率高于成人，与所检查的频带和静息状态无关。我们还发现，在所有频带中，相干值在成人中都比儿童强。有向组内相干性分析表明，儿童的信息流向从前额到顶叶的源，而在成年人中则观察到信息从顶叶流向前额。此外，在成年人中，丘脑皮质连通性是单向的（即，流向皮质区域），而在儿童中是双向的。组间比较证实了对功能和有向连通性的单个体分析的结果。我们的结果表明，功能和有向连通性都对大脑成熟敏感，因为发育中的大脑和成人大脑的功能连接的分布和方向性不同。
