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

项目概要/摘要 语音学习的敏感期发生在6~12月龄之间 作为婴儿的语音处理，这显然是语言习得的最早里程碑之一 在此期间可以可靠地预测以后的语言技能。最近，我的作品展示给 这一时期的语音神经处理首次不仅可以预测个体语法 6 岁时的技能，但也存在典型发育中出现言语和语言障碍的风险 婴儿。这一结果表明敏感期具有重要的临床相关性，并证明 迫切需要进一步了解敏感期的潜在神经机制， 特别是在患有语言障碍的高风险婴儿中它是否可能已经发生改变， 例如发育性语言障碍（DLD）。阐明神经机制并不能 只允许理论扩展以涵盖非典型语言发展，但更多 重要的是，帮助识别语言障碍的早期标志并帮助制定有针对性的治疗方法 早期干预。具体来说，敏感期的特点是言语分歧 处理，从而提高婴儿对母语对比的敏感性，同时提高对母语对比的敏感性 非母语语音对比下降。从理论上讲，这是针对本地人的专业化过程 语言，母语专业化程度较低与语言发展较慢相关。 然而，行为和功能神经影像学研究仅调查了典型的发育 婴儿（低风险），但不包括有沟通障碍家族史的婴儿（高风险）。它是 在此期间，可能已经出现了将高危婴儿与这些婴儿区分开来的差异。 差异可能是高风险人群日后语言困难的根源。目前的Katz ESI 该提案旨在转移焦点，专门检查有家族史的高危婴儿 DLD 并将其与 ~6（开始）、~12（结束）和 ~14（延迟结束）时的低风险婴儿进行比较 敏感期）几个月，其中心理论假设是高危婴儿会 与低风险相比，表现出长期的敏感期或滞后的母语专业化 婴儿。特别是，我们还检查了语音的较高和较低水平的神经过程 就像神经过程之间的联系一样。与语音相关的高级过程 歧视是通过错配反应（MMR）来索引的，而较低级别的感觉编码 语音由复杂的听觉脑干反应（cABR）索引。这两项措施都将 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背后的神经机制，并与 NIDCD 的使命是对言语和语言的紊乱过程进行研究。

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.