Coderre Emily L
Department of Communication Sciences and Disorders, University of Vermont;
J Vis Exp. 2018 Apr 12(134):57217. doi: 10.3791/57217.
Individuals with autism spectrum disorder (ASD) have characteristic deficits in understanding the meaning of language, or semantic processing. However, some evidence indicates that semantic processing of non-linguistic stimuli is intact, suggesting that semantic deficits may be language-specific. To appropriately characterize semantic processing deficits in individuals with ASD, comparison of within-modality linguistic (e.g., written words) and non-linguistic (e.g., pictures) stimuli is required. This paper describes such a methodology that makes use of a semantic priming paradigm during concurrent recording of electroencephalographic (EEG) data. EEG provides a dynamic measure of brain activity that is well-suited to characterize subtle differences in semantic processing that may not be observable at the behavioral level. The semantic priming paradigm presents a prime picture or word (e.g., dog) followed by a target picture or word that is either related (e.g., cat) or unrelated (e.g., pencil) to the prime. This paradigm can thus be used to evaluate semantic processing across different modalities, and to compare lexico-semantic and visuo-semantic processing abilities in individuals with ASD and how they might differ from TD individuals. The specific steps involved in creating the stimuli, performing the EEG testing, and analyzing the EEG data are discussed. Representative results illustrate how the N400 component of the event-related potential (ERP) is reduced following semantically-related prime-target pairs compared to unrelated pairs. Comparisons of the N400 between conditions, modalities, and groups can provide estimates of the success of semantic processing, and can thereby be used to characterize semantic deficits in individuals with ASD or other clinical populations.
患有自闭症谱系障碍（ASD）的个体在理解语言含义或语义处理方面存在特征性缺陷。然而，一些证据表明非语言刺激的语义处理是完整的，这表明语义缺陷可能是特定于语言的。为了恰当地描述ASD个体的语义处理缺陷，需要比较模态内的语言（如书面文字）和非语言（如图像）刺激。本文描述了一种在同步记录脑电图（EEG）数据时利用语义启动范式的方法。EEG提供了一种动态的大脑活动测量方法，非常适合于表征在行为水平上可能无法观察到的语义处理中的细微差异。语义启动范式先呈现一个启动图片或单词（如狗），然后呈现一个与启动词相关（如猫）或不相关（如铅笔）的目标图片或单词。因此，该范式可用于评估不同模态的语义处理，并比较ASD个体与典型发育（TD）个体的词汇语义和视觉语义处理能力以及它们可能存在的差异。文中讨论了创建刺激、进行EEG测试以及分析EEG数据所涉及的具体步骤。代表性结果说明了与不相关对相比，语义相关的启动-目标对之后事件相关电位（ERP）的N400成分是如何降低的。不同条件、模态和组之间N400的比较可以提供语义处理成功程度的估计，从而可用于描述ASD个体或其他临床群体中的语义缺陷。
