Interactive Specialization in Language Impairment

描述（由申请人提供）：本项目将使用功能性磁共振成像（fMRI）检查语言发展的神经基础。在一个纵向设计中，幼儿将被给予单词水平和句子水平的任务，这些任务涉及语音，语义和形态句法处理。我们假设，颞顶叶皮层通过增加与额叶皮层的互动（即连接），在不同的语言表征的发展中变得更加专业化。专业化的特点应该是颞顶叶皮层对利用语言功能不同方面的任务的不同反应的增加。该项目将测试交互式专业化 模型，使发展大脑差异的明确预测[1，2]，但几乎没有直接的 神经影像学证据支持它[19]。该模型的核心原则是，大脑区域之间的相互作用驱动了大脑区域的专门化，以进行某些计算。扩展的互动专业化模型预测，LI的儿童应该缺乏专业化的颞顶叶皮层可能是由于改变颞顶叶和额叶区域之间的相互作用。大脑区域之间的功能连接将通过心理生理学交互（PPI）进行测量，专业化将通过激活差异进行测量，但也可以通过表征相似性分析（RSA）进行测量。在从学前到小学的过渡阶段，对语言发展的考察是重要的，因为这种过渡的特点是掌握复杂的形态句法原则，语义表征的阐述和细化，以及儿童处理音素信息的能力的提高。测试我们总体假设的核心是量化幼儿大脑的变化，以及语言障碍（LI）中出现的差异。以往的功能磁共振成像研究一般采用横断面设计，只检查了一个年龄组，检查了广泛的年龄范围（即从幼儿园到青春期）和/或没有检查多个语言过程。此外，只有少数神经影像学研究检查了儿童LI的大脑基础。我们的项目将克服这些缺点，通过使用纵向的方法来检查幼儿的多种语言过程的发展。纵向的方法很少用于发育神经影像学文献，但对于深入了解什么机制驱动语言发展至关重要。我们项目的一个显著优势是使用基于广泛的行为文献的理论动机的实验任务来研究幼儿大脑发育的创新想法。使用复杂的变化模型也将使我们能够确定语言障碍的纵向增长是否代表了定量与定性的差异，以及神经影像学测量是否可以用来唯一地预测那些可能在语言处理方面进一步落后的儿童。

DESCRIPTION (provided by applicant): This project will examine the neural basis of language development using functional magnetic resonance imaging (fMRI). In a longitudinal design, young children will be given word level and sentence level tasks that tap into phonological, semantic and morpho-syntactic processing. We hypothesize that temporo-parietal cortex becomes more specialized over development for distinct linguistic representations through increasing interaction (i.e. connectivity) with frontal cortex. Specialization should be characterized by increases in differential responses in temporo-parietal cortex to tasks tapping into distinct aspects of linguistic function. This project will test the interactive-specialization model that makes clear predictions of developmental brain differences [1, 2], but has little direct neuroimaging evidence to support it [19]. The central tenet of this model is that interaction between brain regions drives the specialization of brain regions for making certain computations. An extension of the interactive-specialization model predicts that children with LI should have lack of specialization in temporo-parietal cortex perhaps due to altered interaction between temporo-parietal and frontal regions. Functional connectivity between brain regions will be measured with Psychophysiological Interaction (PPI) and specialization will be measured with activation differences, but also with Representational Similarity Analysis (RSA). Examination of language development in the transition from preschool to elementary school is important because this transition is marked by mastery of complex morpho-syntactic principles, elaboration and refinement of semantic representations, and by increases in children's ability to process phonemic information. Central to testing our overarching hypothesis is quantifying brain changes in young children, and differences that emerge in language impairment (LI). Previous fMRI studies have generally used cross-sectional designs and have only examined one age group, have examined a wide age range (i.e. from kindergarten through adolescence) and/or have not examined multiple linguistic processes. Moreover, only a handful of neuroimaging studies have examined the brain basis of LI in children. Our project will overcome these shortcomings by using a longitudinal approach to examine the development of multiple linguistic processes in young children. Longitudinal approaches are rarely used in the developmental neuroimaging literature, but are crucial for gaining insights into what mechanisms drive language development. A significant strength of our project is the use of theoretically motivated experimental tasks based on extensive behavioral literature to investigate innovative ideas regarding brain development in young children. The use of sophisticated change models will also allow us to determine whether the longitudinal growth in language impairment represents a quantitative versus qualitative difference and whether neuroimaging measures can be used to uniquely predict those children who are likely to fall further behind in language processing.