Neural Substrates of Component Lexical Semantic Processes

从单词中提取意义（词汇语义学）对正常的语言功能至关重要。词汇 语义障碍可由多种原因引起，包括发育异常、中风和 退行性疾病，但可能反映对一个或多个组成过程的损害。当前语言 模型已经确定了词汇语义系统的两个性质上不同的组成部分。(1)一个 自动组件能够在词汇输入的毫秒内快速访问语义;（2）受控组件 组件的演化更慢，并指导未恢复的语义信息的策略检索 的自动此外，与这些组件相关的一些过程被认为取决于 传入刺激的模式。该项目的目标是确定这些神经相关性 词汇语义系统的行为上可分离的自动和受控成分， 在视觉和听觉模式上。在一项初步研究中，我们确定了 使用事件相关的视觉提示在健康志愿者中的自动和控制的词汇语义加工 功能磁共振成像和启动词汇判断任务。提出了一系列类似的研究， 准确地说，额叶和颞叶脑区在词汇语义成分中的作用 系统该设计的新颖之处在于，自动和受控的语义启动条件将得到比较 直接，使用与行为研究中使用的相同的随机设计。有三个目标。的 第一个目标是更精确地描述左额叶在视觉线索控制提取中的作用 词汇语义信息。第二个目标是更准确地描述左颞叶的作用， 视觉提示的自动词汇语义处理。第三个目标是识别神经区域 涉及到与视觉相关的词汇语义重叠，并且与视觉相关的词汇语义分离， 词汇语义学线索识别与参与的组成过程相关的神经系统 从单词中提取意义对于理解单词的结构和组织至关重要。 词汇语义系统，并应帮助诊断和语言障碍的康复。

Extracting meaning from words (lexical semantics) is critical to normal language functioning. Lexical semantic impairment can result from a variety of causes including developmental abnormalities, stroke and degenerative diseases but may reflect damage to one or more component processes. Current language models have identified two qualitatively different components of the lexical semantic system. (1) An automatic component enables rapid access to semantics within milliseconds of lexical input; (2) a controlled component evolves more slowly and guides strategic retrieval of semantic information not recovered automatically. In addition, some processes associated with these components are thought to depend upon the modality of incoming stimuli. The objective of the project is to identify the neural correlates of these behaviorally separable automatic and controlled components of the lexical semantic system, within and across visual and auditory modalities. In a preliminary study, we identified dissociable neural correlates of visually cued automatic and controlled lexical semantic processing in healthy volunteers using event-related fMRI and a primed lexical decision task. A series of similar studies are proposed to characterize more precisely the roles of several frontal and temporal lobe brain regions in components of the lexical semantic system. The design is novel in that automatic and controlled semantic priming conditions will becompared directly, using randomized designs identical to those used in behavioral research. There are three goals. The first goal is to characterize more precisely the role of a left frontal region in visually cued controlled retrieval of lexical semantic information. The second goal is to characterize more precisely the role of a left temporal region in visually cued automatic lexical semantic processing. The third goal is to identify neural regions involved in auditorily cued lexical semantics that overlap, and are dissociable from, those involved in visually cued lexical semantics. Identifying neural systems associated with component processes involved in extracting meaning from words is of central importance to understanding the structure and organization of the lexical semantic system and should aid diagnosis and rehabilitation of language disorders.