Functional significance of the N400 potential

N400 电位的功能意义

• 批准号: 194517-2010
• 负责人: Debruille, Bruno
• 金额: $ 1.97万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=476695
• 关键词: Functional; significance; N400; potential

This research focuses on one of the mechanisms that allow the understanding of the meaning of the occurrence of items, such as words, faces and objects, in their context. This mechanism is indexed by a negative electrical field that is recorded by placing electrodes on the head. This field is maximum 400 milliseconds after the onset of the stimulus and is thus called the N400. It is thought to reflect processes dealing with memory representations corresponding to the item. However, we performed a series of work suggesting that it could index processes dealing with memory representations corresponding to inappropriate stimuli, whether they correspond a) to the expectation for other items, b) to the no longer relevant context(s) in which the item was previously encuntered or c) to items that resemble the stimulus. We developed the hypothesis that the N400 could index the inhibition of all types of inaccurate representations. We tested this hypothesis and developed a new type of experiments to focus on the inhibition of the first type of representations: those that correspond to expectations that are disconfirmed by the stimulus. This new type of experiments includes the presentations of only a few items which are massively repeated. It could allow the study of the N400 processes corresponding to individual concepts. The present research project aims at further studying the functional significance of the N400 potential by using this new type of experiments and a) by manipulating separately the expectation and the item itself, to verify that the N400 elicited by the item depend on the 1st type of manipulation; b) by testing that the N400 elicited by the highly repeated items of these experiments are impervious to the frequency with which the item is used in the language and to the number of letters of the item. We also want to see whether N400 can be elicited by highly repeated stimuli other than words: that is, faces and object; c) by looking for behavioural correlates of the inhibition with highly repeated word; and d) by using ambiguous words without massive repetition to see whether the N400 indexes the inhibition of the meaning that is inappropriate to the context and the inhibition of the context in which the ambiguous word was first encountered in the experiment.

本研究关注的是一种机制，这种机制允许理解单词、面孔和物体等项目在其上下文中出现的意义。这种机制是通过在头部放置电极记录的负电场来指示的。这个区域在刺激开始后最多出现400毫秒，因此被称为N400。它被认为反映了处理与项目相对应的内存表示的进程。然而，我们进行了一系列的工作，表明它可以索引处理与不适当刺激相对应的记忆表征的过程，无论它们对应于a)对其他项目的期望，b)对先前遇到的项目不再相关的上下文，还是c)与刺激相似的项目。我们提出假设，N400可以索引所有类型的不准确表征的抑制。我们对这一假设进行了测试，并开发了一种新的实验，专注于第一种表征的抑制：那些与刺激不确定的期望相对应的表征。这种新类型的实验包括只展示几个大量重复的项目。它可以研究对应于单个概念的N400过程。本研究拟利用这一新型实验进一步研究N400电位的功能意义，a)分别操纵期望和项目本身，验证项目所激发的N400依赖于第一种操作；b)通过测试由这些实验中高度重复的项目引起的N400不受该项目在语言中使用的频率和项目的字母数量的影响。我们还想看看N400是否可以被高度重复的刺激所激发，而不是单词，即面孔和物体；C)通过寻找与高度重复单词抑制的行为相关性；d)在不大量重复的情况下使用歧义词，观察N400是否对与上下文不合适的意义的抑制以及实验中歧义词首次出现的上下文的抑制进行索引。