语境调节词汇语义和后词汇语义加工的大脑动态机制

The word recognition involved two different cognitive processes. One is the lexical semantic processing in which the bottom-up phonemic or orthographic input is matched to templates in the mental lexicon to access the semantic information. The other is the post-lexical semantic processing in which top-down and slower controlled processes operate to retrieve and select the semantic information based on our knowledge and the context. And the neural dynamics of the lexical semantic and post-lexical semantic processing is the hot topic and is not yet well understood in the field. In this proposal, we plan to use a new technique which calls EROS (Event-Related Optical Signal) which has both high temporal (less than 100ms) and spatial resolution (5-10mm). And the EROSs data will be recorded simultaneously with ERPs to explore the neural dynamics of lexical semantic processing and post-lexical semantic processing by monitoring the time course of the left middle temporal and left inferior frontal gyrus activation. Specifically, first, we study the neural dynamics of the lexical semantic and post-lexical semantic processing in the single word recognition. Second, we will manipulate the context before the target word in three dimensions: (1) manipulate conscious level of the context information; (2) manipulate the level of context constraint; (3) manipulate the relation between the sentence context and word context, to study whether and how context modulate the neural dynamics of the lexical semantic and post-lexical semantic processing.

当我们识别一个词汇时，需要进行自下而上从视觉信息抽取词汇语义的词汇语义加工，以及自上而下根据经验和即时的语境策略性的选择和提取词汇语义信息的后词汇语义加工这两种加工。词汇语义和后词汇语义加工的大脑动态过程是研究中的热点和难点问题。在本项目中，我们将使用高时间和空间分辨率的EROS技术，并采用EROS和ERP同步采集的方式，通过考察左侧颞中回和左侧额下回激活的时间过程，分析词汇语义和后词汇语义加工的大脑动态机制。具体来说，我们首先在无语境下的单个词汇识别过程中词汇和后词汇语义加工的大脑动态过程。其次在三个方面系统地操纵语境：（1）操纵语境信息进入意识状态的程度；（2）操纵语境信息的强度；（3）操纵不同层面语境信息之间的关系，系统而全面地考察语境信息调节词汇和后词汇语义加工的大脑动态机制。

在本项目中，我们采用了行为学、眼动、Event-Related Potentials以及Event-related Optical Signals (EROS)技术，研究在实时的语言处理过程中，语境是如何起作用，以及不同语境下对语言处理过程的调节机制。具体来说，我们的研究分别对：语境对句法表征的影响机制，和语境对于词汇和后词汇语义加工的大脑动态调节机制展开系统的研究。本项目有几项重要的发现：（1）中文阅读者在阅读过程中可以快速自动地利用语境信息建立独立于语义的句法结构表征；（2）语境的熟悉程度会调节句法结构表征的时间进程；（3）语境虽然在单个词汇的加工过程中会改变词汇语义和后词汇语义的加工时间进程，但是在一般的语言理解过程中更多是改变加工的程度，而非加工的时间进程。因此这个项目的执行，为我们深入地了解语境对于语言处理过程中的精细的作用机制提供了重要的实验证据。