Interactive Specialization in Language Impairment

描述（由申请人提供）：本项目将使用功能磁共振成像（fMRI）研究语言发展的神经基础。在纵向设计中，幼儿将被赋予单词水平和句子水平的任务，这些任务涉及语音、语义和词形句法处理。我们假设，通过增加与额叶皮层的相互作用（即连通性），颞顶叶皮层在不同语言表征的发展过程中变得更加专业化。专门化的特征应该是颞顶叶皮层对涉及语言功能不同方面的任务的不同反应的增加。这个项目将测试交互专门化

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.