Biological Substrates for Language

描述（由申请人提供）：拟议研究的长期目标是了解语言大脑侧化个体差异的生物学机制。了解决定正常脑组织固有变异性的因素对于有效治疗单侧脑损伤患者至关重要。有人建议，个人在不同的程度和一致性的左半球的优势，这些变化具有行为意义的语言处理。一个正常人的大样本将在一系列的语言任务中进行测试，其中刺激被呈现给左半球和右半球。这些任务测量基本的单词识别和语义检索过程。将进行结构性磁共振成像（MRI），以评估后部（颞平面、顶平面、Heschl氏回）和前部（三角部、扣带和副扣带沟）脑区的不对称性。假设：（1）个体在关键皮层区域的不对称程度上存在差异，这种结构差异与语言功能的半球间组织有关;（2）个体在不对称性的一致性方面存在差异，因此有些人在任务和大脑区域之间具有一致的中度不对称模式，而另一些人则表现出随机偏离总体平均值的行为和解剖学不对称性;（3）具有一致的、典型的不对称性的个体在各种非侧化词汇任务中表现出更高的速度和准确性。虽然发育性和获得性脑功能障碍的治疗是单独进行的，但对正常功能的理解主要基于组平均值。因此，对未受伤人群个体差异的研究可以为大脑侧化的基础科学和临床应用提供重要的桥梁。

DESCRIPTION (provided by applicant): The long-term objective of the proposed research is to understand the biological mechanisms underlying individual differences in cerebral lateralization for language. Understanding the factors that determine the variability inherent in normal brain organization is essential in order to effectively treat individuals with unilateral brain injuries. It is proposed that individuals vary both in the degree and consistency of left hemisphere predominance and that these variations have behavioral significance for language processing. A large sample of normal persons will be tested in a series of linguistic tasks in which stimuli are presented to the left and right hemispheres. The tasks measure both basic word recognition, and semantic retrieval, processes. Structural magnetic resonance imaging (MRI) will be performed to assess asymmetries in posterior (planum temporale, planum parietale, Heschl's gyrus) and anterior (pars triangulars, cingulate and paracingulate sulcus) brain regions. It is hypothesized that (1) individuals differ in the extent to which critical cortical regions are asymmetrical and that this structural variability is linked to the inter-hemispheric organization of language function; (2) individuals differ in the consistency of their asymmetries such that some have a consistent pattern of moderate asymmetries across tasks and brain regions, while others show behavioral and anatomical asymmetries that depart from the population mean randomly; and (3) individuals with consistent, typical asymmetries will demonstrate greater speed and accuracy across a variety of nonlateralized lexical tasks. Although treatment for developmental and acquired brain dysfunction is administered individually, the understanding of normal function is based primarily on group averages. Hence, the study of individual differences in uninjured populations can provide a critical bridge between the basic science of cerebral lateralization and its clinical application.