Caffarra Sendy, Lizarazu Mikel, Molinaro Nicola, Carreiras Manuel
Division of Developmental-Behavioral Pediatrics, Stanford University School of Medicine, Stanford, California 94305-5101
Stanford University Graduate School of Education, Stanford, California 94305.
J Neurosci. 2021 Jul 7;41(27):5867-5875. doi: 10.1523/JNEUROSCI.3021-20.2021.
The ability to establish associations between visual objects and speech sounds is essential for human reading. Understanding the neural adjustments required for acquisition of these arbitrary audiovisual associations can shed light on fundamental reading mechanisms and help reveal how literacy builds on pre-existing brain circuits. To address these questions, the present longitudinal and cross-sectional MEG studies characterize the temporal and spatial neural correlates of audiovisual syllable congruency in children (age range, 4-9 years; 22 males and 20 females) learning to read. Both studies showed that during the first years of reading instruction children gradually set up audiovisual correspondences between letters and speech sounds, which can be detected within the first 400 ms of a bimodal presentation and recruit the superior portions of the left temporal cortex. These findings suggest that children progressively change the way they treat audiovisual syllables as a function of their reading experience. This reading-specific brain plasticity implies (partial) recruitment of pre-existing brain circuits for audiovisual analysis. Linking visual and auditory linguistic representations is the basis for the development of efficient reading, while dysfunctional audiovisual letter processing predicts future reading disorders. Our developmental MEG project included a longitudinal and a cross-sectional study; both studies showed that children's audiovisual brain circuits progressively change as a function of reading experience. They also revealed an exceptional degree of neuroplasticity in audiovisual neural networks, showing that as children develop literacy, the brain progressively adapts so as to better detect new correspondences between letters and speech sounds.
在视觉对象和语音之间建立关联的能力对人类阅读至关重要。了解获取这些任意视听关联所需的神经调节，有助于揭示基本的阅读机制，并有助于揭示读写能力如何建立在预先存在的脑回路基础之上。为了解决这些问题，目前的纵向和横断面脑磁图（MEG）研究对正在学习阅读的儿童（年龄范围4至9岁；22名男性和20名女性）视听音节一致性的时间和空间神经相关性进行了表征。两项研究均表明，在阅读教学的最初几年里，儿童逐渐在字母和语音之间建立视听对应关系，这种对应关系在双峰呈现的前400毫秒内即可检测到，并会激活左颞叶皮质的上部。这些发现表明，儿童会根据阅读经验逐渐改变他们处理视听音节的方式。这种特定于阅读的大脑可塑性意味着（部分）调用预先存在的用于视听分析的脑回路。将视觉和听觉语言表征联系起来是高效阅读发展的基础，而视听字母处理功能失调则预示着未来的阅读障碍。我们的发育性脑磁图项目包括一项纵向研究和一项横断面研究；两项研究均表明，儿童的视听脑回路会随着阅读经验的变化而逐渐改变。它们还揭示了视听神经网络中异常程度的神经可塑性，表明随着儿童读写能力的发展，大脑会逐渐适应，以便更好地检测字母和语音之间的新对应关系。
