Neurosciences and Mental Health, SickKids Research Institute, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada.
Epilespy Research Program of the Ontario Brain Institute, Toronto, ON, Canada.
Dev Sci. 2021 Jan;24(1):e12984. doi: 10.1111/desc.12984. Epub 2020 Jun 2.
As we listen to speech, our ability to understand what was said requires us to retrieve and bind together individual word meanings into a coherent discourse representation. This so-called semantic unification is a fundamental cognitive skill, and its development relies on the integration of neural activity throughout widely distributed functional brain networks. In this proof-of-concept study, we examine, for the first time, how these functional brain networks develop in children. Twenty-six children (ages 4-17) listened to well-formed sentences and sentences containing a semantic violation, while EEG was recorded. Children with stronger vocabulary showed N400 effects that were more concentrated to centroparietal electrodes and greater EEG phase synchrony (phase lag index; PLI) between right centroparietal and bilateral frontocentral electrodes in the delta frequency band (1-3 Hz) 1.27-1.53 s after listening to well-formed sentences compared to sentences containing a semantic violation. These effects related specifically to individual differences in receptive vocabulary, perhaps pointing to greater recruitment of functional brain networks important for top-down semantic unification with development. Less skilled children showed greater delta phase synchrony for violation sentences 3.41-3.64 s after critical word onset. This later effect was partly driven by individual differences in nonverbal reasoning, perhaps pointing to non-verbal compensatory processing to extract meaning from speech in children with less developed vocabulary. We suggest that functional brain network communication, as measured by momentary changes in the phase synchrony of EEG oscillations, develops throughout the school years to support language comprehension in different ways depending on children's verbal and nonverbal skill levels.
当我们聆听言语时，理解言语的能力要求我们将各个单词的含义提取并整合到连贯的语篇表示中。这种所谓的语义统一是一种基本的认知技能，其发展依赖于整个广泛分布的功能大脑网络中神经活动的整合。在这项概念验证研究中，我们首次研究了这些功能大脑网络在儿童中的发展情况。我们对 26 名儿童（年龄 4-17 岁）进行了测试，让他们聆听结构完整的句子和包含语义违规的句子，同时记录他们的脑电图。词汇量较大的儿童在聆听结构完整的句子后 1.27-1.53 秒，与聆听包含语义违规的句子相比，其 N400 效应更集中于中央顶区电极，右中央顶区和双侧额中央电极之间的 delta 频段（1-3 Hz）的脑电图相位同步（相位滞后指数；PLI）更强。这些效应与接受性词汇量的个体差异具体相关，这可能表明随着发展，与自上而下的语义统一相关的功能大脑网络的更大招募。技能较低的儿童在关键单词出现后 3.41-3.64 秒，对违规句子的 delta 相位同步性更强。这种较晚的效应部分由非言语推理的个体差异驱动，这可能表明词汇量发育较差的儿童通过非言语补偿处理从言语中提取意义。我们认为，功能性大脑网络的通讯，如脑电图振荡相位同步性的瞬间变化所测量的那样，在整个学年中发展，根据儿童的言语和非言语技能水平，以不同的方式支持语言理解。
