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: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=523221
• 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.

本研究的重点之一的机制，允许的项目，如单词，面孔和对象，在其上下文中出现的意义的理解。 这种机制是通过在头部放置电极来记录的负电场来索引的。这个场在刺激开始后400毫秒最大，因此被称为N400。它被认为反映了处理与项目相对应的记忆表征的过程。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，无论它们是否对应于a）对其他项目的期望，B）不再相关的上下文（其中项目先前被纠缠）或c）类似于刺激的项目。我们提出了一个假设，即N400可以指示所有类型的不准确表征的抑制。 我们测试了这一假设，并开发了一种新的实验，专注于第一种表征的抑制：那些对应于被刺激否定的期望的表征。这种新类型的实验包括仅呈现大量重复的少数项目。它可以允许研究与各个概念相对应的N400过程。本研究的目的是利用这一新的实验方法进一步研究N400电位的功能意义：（1）通过分别操纵期望和项目本身，验证项目诱发的N400电位依赖于第一种操纵; B）通过测试这些实验中高度重复的项目所引起的N400不受该项目在语言中使用的频率和字母的数量的影响，item.我们还想看看N400是否可以被高度重复的刺激而不是单词所诱发：即面孔和物体; c）通过寻找与高度重复的单词抑制的行为相关性;（d）通过使用没有大量重复的歧义词，看看N400是否索引了对不适合上下文的含义的抑制和对上下文的抑制，在实验中第一次遇到了歧义词。