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: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=506424
• 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.

这项研究的重点是一种能够理解词语、面孔和物体等项目在其上下文中出现的含义的机制。 该机制通过将电极放置在头上来记录的负电场来指示。该场在刺激开始后 400 毫秒内达到最大值，因此称为 N400。它被认为反映了处理与该项目相对应的内存表示的过程。然而，我们进行了一系列工作，表明它可以对处理与不适当刺激相对应的记忆表征的过程进行索引，无论它们是否对应于a）对其他项目的期望，b）与先前遇到的项目不再相关的上下文或c）与类似于刺激的项目相对应。我们提出了这样的假设：N400 可以对所有类型的不准确表征的抑制进行索引。 我们测试了这一假设，并开发了一种新型实验，重点关注对第一类表征的抑制：那些与被刺激所否定的期望相对应的表征。这种新型实验仅包括大量重复的少数项目的呈现。它可以允许研究与各个概念相对应的 N400 过程。本研究项目旨在通过使用这种新型实验进一步研究 N400 潜力的功能意义，并且 a）通过分别操纵期望和项目本身，以验证项目引发的 N400 取决于第一种操纵； b) 通过测试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以及该项目的字母数量的影响。我们还想看看 N400 是否可以通过单词以外的高度重复的刺激来引发：即面部和物体； c) 通过寻找与高度重复的单词的抑制行为相关； d）通过使用没有大量重复的歧义词来观察N400是否索引了对与上下文不合适的含义的抑制以及对实验中第一次遇到歧义词的上下文的抑制。