Franklin Michael S, Dien Joseph, Neely James H, Huber Elizabeth, Waterson Lauren D
Department of Psychology, Tulane University, USA.
Clin Neurophysiol. 2007 May;118(5):1053-68. doi: 10.1016/j.clinph.2007.01.012. Epub 2007 Mar 1.
To determine whether ERP components can differentiate between the semantic priming mechanisms of automatic spreading activation, expectancy, and semantic matching.
The present study manipulated two factors known to differentiate semantic priming mechanisms: associations between words (forward, backward, and symmetrical) and prime-target stimulus onset asynchrony (SOA). Twenty-six participants were tested in each SOA condition while high-density 128-channel data were collected. Principal components analysis was applied to separate the ERP components.
Priming was observed for all conditions. Three semantic components were present: (1) the standard N400 effect for symmetric and forward priming pairs at both short and long SOAs, (2) an N300 for the long SOA symmetric priming pairs, and (3) a right-lateralized posterior N400RP for long SOA backward priming pairs.
Results suggest that the N300 reflects expectancy, but only for categorical and/or semantic similarity priming. Results further suggest that the N400RP is a replicable ERP component that responds to semantic matching. There is also some evidence that the N400 indirectly responds to both ASA and expectancy, perhaps as part of a post-lexical updating process and that backward priming at short SOAs is different from that at long SOAs.
Improved understanding of the semantic properties of the N400 and related ERP components may increase their utility for understanding language processes and for diagnostic purposes.
确定事件相关电位（ERP）成分能否区分自动扩散激活、预期和语义匹配这三种语义启动机制。
本研究操纵了两个已知可区分语义启动机制的因素：词之间的关联（正向、反向和对称）以及启动刺激与目标刺激的起始时间间隔（SOA）。在每种SOA条件下对26名参与者进行测试，同时收集高密度128通道数据。应用主成分分析来分离ERP成分。
在所有条件下均观察到启动效应。存在三种语义成分：（1）在短SOA和长SOA时，对称和正向启动对的标准N400效应；（2）长SOA对称启动对的N300；（3）长SOA反向启动对的右侧化后N400RP。
结果表明，N300反映预期，但仅针对范畴和/或语义相似性启动。结果还表明，N400RP是一个可重复的ERP成分，对语义匹配有反应。也有一些证据表明，N400可能作为词汇后更新过程的一部分，对自动扩散激活（ASA）和预期都有间接反应，并且短SOA时的反向启动与长SOA时不同。
对N400及相关ERP成分语义特性的深入理解可能会提高它们在理解语言过程和诊断方面的效用。
