Neurodevelopmental plasticity of language: From bottom-up to top-down

描述(申请人提供)：功能磁共振应用于发育变化的研究已有十多年。越来越多的功能磁共振研究考察了语言组织中与年龄相关的变化。然而，现有的研究主要着眼于在横断面设计中检测儿童和成人之间的差异，而且有限，因为它们只捕获了单个时间点的发展，因此这些认知变化随着时间的推移发生的机制仍然相当不确定。许多现有的研究也缺乏解释为什么语言组织应该在儿童时期发生变化以及这种变化是如何发生的理论。更好地了解认知变化的机制可能会拓宽我们对认知发展的理解，阐明非典型发展的原因，并有可能为我们诊断、治疗和预防发育障碍提供信息。目前的建议建立在语言发展的综合理论基础上，该理论预测组织从早期以感觉运动为基础的(自下而上)加工，到儿童和成年后期更强的自上而下控制加工。该理论应用于两个语言任务，挖掘了语言发展的两个主要组成部分(词汇语义和形态句法)，产生了关于发展变化的具体假设，这些假设将在横向和纵向分析中得到检验。构造性和退化性神经变化机制的理论揭示了大脑区域将与年龄相关的差异参与语言网络的假设。这些目标将使用非侵入性技术结构磁共振成像(MRI)、功能磁共振成像和功能连接磁共振成像(FcMRI)来绘制结构和功能大脑网络图。在功能成像过程中，受试者将完成一系列的语言任务：词汇语义判断(评估句子描述宾语的准确性)和形态合成判断(评估句子的语法性)。参与者将在7岁或9岁进行最初的成像研究，并将每隔12个月再次扫描一次，为研究提供纵向组成部分。此外，标准化的认知测量将在扫描仪之外进行，以提供与成像数据相关的额外数据，从而考虑到发育和能力的个体差异。

DESCRIPTION (provided by applicant): Functional MRI has been applied to the study of developmental change for over a decade. A growing number of fMRI studies have examined age-related changes in language organization. However, existing studies have predominantly targeted the detection of differences between children and adults in crosssectional designs and are limited as they only capture development at a single point in time, and thus the mechanisms by which these cognitive changes occur over time is still quite uncertain. Also absent from many existing studies are the theories explaining why language organization should be expected to change in childhood and how that change occurs. A better understanding of the mechanisms of cognitive change might broaden our understanding of cognitive development, elucidate the causes of atypical development, and could potentially inform our diagnosis, treatment, and prevention of developmental disorders. The current proposal is founded on a comprehensive theory of language development, which predicts organization from predominantly sensorimotor-based (bottom-up) processing in early stages to more strongly top-down controlled processing in later childhood and adulthood. Applied to two language tasks that tap into the two primary components of language development (lexicosemantic and morphosyntactic), this theoretical perspective generates specific hypotheses about developmental change that will be examined both in cross-sectional and longitudinal analyses. Theories of both constructive and regressive neural mechanisms of change inform the hypotheses that brain regions will have age-related differential involvement in language networks. These aims will be achieved using the noninvasive techniques of structural magnetic resonance imaging (MRI), functional MRI, and functional connectivity MRI (fcMRI) to map structural and functional brain networks. During functional imaging, subjects will complete a panel of language tasks: lexical semantic decision (assessing accuracy of sentences describing objects) and morphosyntactic judgment (assessing grammaticality of sentences). Participants will be age seven or nine for the initial imaging study, and will be scanned once more at twelve month intervals, providing a longitudinal component to the study. In addition, standardized cognitive measures will be administered outside the scanner to provide additional data for correlation with imaging data, allowing individual differences in development and ability to be taken into account.