Quantifying the degree to which genetic and environmental factors shape brain network connectivity is critical to furthering our understanding of the developing human brain. Sleep, a state of sensory disengagement, provides a unique opportunity to study brain network activity noninvasively by means of sleep electroencephalography (EEG) coherence. We conducted a high-density sleep EEG study in monozygotic (MZ; n = 38; mean age = 12.46; 20 females) and dizygotic (DZ; n = 24; mean age = 12.50; 12 females) twins to assess the heritability of sleep EEG coherence in early adolescence—a period of significant brain rewiring. Structural equation modeling was used to estimate three latent factors: genes, environmental factors shared between twins and environmental factors unique to each twin. We found a strong contribution of unique environmental factors (66% of the variance) and moderate genetic influence (19% of the variance) on sleep EEG coherence across frequencies and sleep states. An exception to this was sleep spindle activity, an index of the thalamocortical network, which showed on average a genetic contribution of 48% across connections. Furthermore, we observed high intraindividual stability of coherence across two consecutive nights suggesting that despite only a modest genetic contribution, sleep EEG coherence is like a trait. Our findings in adolescent humans are in line with earlier findings in animals that show the primordial cerebral map and its connections are plastic and it is through interaction with the environment that the pattern of brain network connectivity is shaped. Therefore, even in twins living together, small differences in the environment may cascade into meaningful differences in brain connectivity.

中文翻译：

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环境因素影响青春期早期的睡眠 EEG 连通性。

量化遗传和环境因素塑造大脑网络连接的程度对于进一步了解人类大脑的发展至关重要。睡眠是一种感觉脱离的状态，它提供了一个独特的机会，可以通过睡眠脑电图 (EEG) 相干性无创地研究大脑网络活动。我们在同卵（MZ；n  = 38；平均年龄 = 12.46；20 名女性）和异卵（DZ；n = 24; 平均年龄 = 12.50；12 名女性）双胞胎，以评估青春期早期睡眠脑电图一致性的遗传性——这是大脑重新布线的重要时期。结构方程模型用于估计三个潜在因素：基因、双胞胎之间共享的环境因素和每个双胞胎独有的环境因素。我们发现独特的环境因素（方差的 66%）和中等遗传影响（方差的 19%）对不同频率和睡眠状态的睡眠 EEG 一致性有很大贡献。一个例外是睡眠纺锤波活动，这是一种丘脑皮质网络的指数，平均而言，它对连接的遗传贡献为 48%。此外，我们观察到连续两个晚上的高个体内一致性稳定性表明，尽管只有适度的遗传贡献，睡眠脑电图连贯性就像一个特征。我们在青少年人类中的发现与动物的早期发现一致，这些发现显示原始大脑图及其连接是可塑的，并且正是通过与环境的相互作用来塑造大脑网络连接的模式。因此，即使双胞胎生活在一起，环境的微小差异也可能会导致大脑连接的有意义的差异。