Neural mechanisms underlying the sensitive period for phonetic learning in infants at-risk for Developmental Language Disorder

项目摘要/摘要 语音学习的敏感期发生在6~12个月龄之间 显然是语言习得的最早里程碑之一，如婴儿的语音处理 在此期间可以可靠地预测以后的语言技能。最近，我的工作显示了 这是第一次在这一时期对语音的神经处理不仅可以预测个体语法 6岁的技能，但在典型的发展中也有发展言语和语言障碍的风险 婴儿。这一结果提示了敏感期的重要临床相关性，并证明了 迫切需要进一步了解敏感期的潜在神经机制， 尤其是在语言障碍的高危婴儿身上，它是否已经发生了变化， 如发育性语言障碍(DLD)。阐明神经机制不会 只允许将理论扩展到包含非典型语言发展，但更多 重要的是，帮助识别语言障碍的早期标记，并帮助开发有针对性的 早期干预。具体地说，敏感期的特点是言语上的分歧。 处理过程中，婴儿对母语对比的敏感度提高，而对母语的敏感度 非母语的讲话与衰退形成对比。从理论上讲，这是一个本地人的专业化过程 语言，母语专业化程度较低与语言增长较慢相关。 然而，行为和功能神经成像研究只研究了典型的发育 婴儿(低风险)，但不是有沟通障碍家族史的婴儿(高风险)。它是 可能在这段时间内已经出现了差异，将高危婴儿和这些 差异可能是高危人群未来语言困难的基础。目前的Katz ESI 该提案旨在转移重点，专门检查有家族史的高危婴儿 DLD，并在~6(开始)、~12(结束)和~14(延迟结束)时与低风险婴儿比较 敏感期)个月的年龄，核心理论假设是高危婴儿 证明敏感期较长，或母语专业化认证落后于低风险 婴儿。特别是，我们还研究了语音的高级和低级神经过程。 就像神经过程之间的联系一样。与语音相关的更高级别的过程 辨别通过失配反应(MMR)来索引，而较低水平的感觉编码 语音以复杂听觉脑干反应(CABR)为索引。这两项措施都将是 与脑磁图(MEG)同时获得。总之，拟议的研究将 帮助揭示非典型语言发展的神经机制，并与 NIDCD的使命是对言语和语言的无序过程进行研究。

Project Summary/Abstract The sensitive period for phonetic learning, which occurs between 6~12 months of age, is demonstrably one of the earliest milestones for language acquisition, as infants’ speech processing during this period can reliably predict later language skills. Most recently, my work has shown for the first time that neural processing of speech during this period can predict not only individual grammar skills at 6 years, but also the risk of developing speech and language disorders in typically developing infants. This result suggests an important clinical relevance of the sensitive period and demonstrates a crucial need to further understand the underlying neural mechanisms of the sensitive period, particularly whether it may already be altered in infants at high-risk of developing language disorders, such as the developmental language disorder (DLD). Elucidating the neural mechanism would not only allow for the expansion of theories to encompass atypical language development, but more importantly, help identify early markers for language disorders and aid in the development of targeted early interventions. Specifically, the sensitive period is characterized by a divergence in speech processing, whereby infants’ sensitivity for native speech contrasts improves while sensitivity for nonnative speech contrasts declines. It is theorized to be a specialization process for the native language, where less native language specialization is associated with slower language growth. However, behavioral and functional neuroimaging studies have only investigated typically developing infants (Low-Risk), but not infants with a family history of communication disorders (High-Risk). It is possible that differences already emerge during this period that separate High-Risk infants and these differences may underlie later language difficulties in the High-Risk population. The current Katz ESI proposal aims to shift the focus and specifically examine High-Risk infants with a family history of DLD and compare them with Low-Risk infants at ~6 (start), ~12 (end) and ~14 (delayed end of sensitive period) months of ages, with the central theoretical hypothesis that High-Risk infants would demonstrate a protracted sensitive period, or a lagged native language specialization than Low-Risk infants. Particularly, we examine both higher and lower levels of neural processes for speech, as well as in the link between the neural processes. The higher-level processes related to speech discrimination is indexed by the mismatch response (MMR) while lower-level sensory encoding of speech is indexed by the complex auditory brainstem response (cABR). Both measures will be obtained simultaneously with Magnetoencephalography (MEG). Together, the proposed study will help uncover neural mechanisms underlying atypical language development and perfectly aligns with the mission of NIDCD to conduct research in disordered processes of speech and language.