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

描述（由申请人提供）：功能性MRI应用于发育变化研究已有十多年的历史。越来越多的功能磁共振成像研究已经研究了语言组织中与年龄相关的变化。然而，现有的研究主要针对横断面设计中儿童和成人之间的差异的检测，并且由于它们仅捕获单个时间点的发展，因此这些认知变化随时间发生的机制仍然非常不确定。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，阐明非典型发育的原因，并可能为我们的诊断、治疗和预防发育障碍提供信息。目前的建议是建立在语言发展的综合理论基础上的，该理论预测语言组织从早期主要基于感觉运动（自下而上）的加工到儿童后期和成年期更强烈的自上而下控制的加工。应用于两个语言任务，挖掘语言发展的两个主要组成部分（词汇语义和形态句法），这一理论视角产生了关于发展变化的具体假设，将在横断面和纵向分析中进行检验。建设性和退化性神经变化机制的理论都提出了这样的假设，即大脑区域在语言网络中具有与年龄相关的差异参与。这些目标将通过结构磁共振成像（MRI）、功能MRI和功能连接MRI （fcMRI）的非侵入性技术来实现，以绘制结构和功能脑网络。在功能成像过程中，受试者将完成一组语言任务：词汇语义决策（评估句子描述对象的准确性）和形态句法判断（评估句子的语法性）。初始成像研究的参与者年龄为7岁或9岁，每隔12个月再扫描一次，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外进行，以提供与成像数据相关的额外数据，从而考虑到个体在发育和能力方面的差异。

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.