Drakesmith Mark, El-Deredy Wael, Welbourne Stephen
Neuropsychobiology. 2015;72(1):46-56. doi: 10.1159/000379752.
Reading words for meaning relies on orthographic, phonological and semantic processing. The triangle model implicates a direct orthography-to-semantics pathway and a phonologically mediated orthography-to-semantics pathway, which interact with each other. The temporal evolution of processing in these routes is not well understood, although theoretical evidence predicts early phonological processing followed by interactive phonological and semantic processing.
This study used electroencephalography-event-related potential (ERP) analysis and magnetoencephalography (MEG) source localisation to identify temporal markers and the corresponding neural generators of these processes in early (∼200 ms) and late (∼400 ms) neurophysiological responses to visual words, pseudowords and consonant strings.
ERP showed an effect of phonology but not semantics in both time windows, although at ∼400 ms there was an effect of stimulus familiarity. Phonological processing at ~200 ms was localised to the left occipitotemporal cortex and the inferior frontal gyrus. At 400 ms, there was continued phonological processing in the inferior frontal gyrus and additional semantic processing in the anterior temporal cortex. There was also an area in the left temporoparietal junction which was implicated in both phonological and semantic processing. In ERP, the semantic response at ∼400 ms appeared to be masked by concurrent processes relating to familiarity, while MEG successfully differentiated these processes.
The results support the prediction of early phonological processing followed by an interaction of phonological and semantic processing during word recognition. Neuroanatomical loci of these processes are consistent with previous neuropsychological and functional magnetic resonance imaging studies. The results also have implications for the classical interpretation of N400-like responses as markers for semantic processing.
为理解词义而阅读依赖于正字法、语音和语义处理。三角模型表明存在一条直接的正字法到语义的通路以及一条语音介导的正字法到语义的通路，这两条通路相互作用。尽管理论证据预测早期是语音处理，随后是语音和语义的交互处理，但这些通路中处理过程的时间演变尚不清楚。
本研究使用脑电图 - 事件相关电位（ERP）分析和脑磁图（MEG）源定位来识别对视觉单词、假词和辅音串的早期（约200毫秒）和晚期（约400毫秒）神经生理反应中这些过程的时间标记和相应的神经发生器。
ERP显示在两个时间窗口中都有语音效应但没有语义效应，尽管在约400毫秒时有刺激熟悉度的效应。约200毫秒时的语音处理定位于左侧枕颞叶皮层和额下回。在400毫秒时，额下回持续进行语音处理，颞前叶皮层进行额外的语义处理。在左侧颞顶叶交界处也有一个区域与语音和语义处理都有关。在ERP中，约400毫秒时的语义反应似乎被与熟悉度相关的并发过程所掩盖，而MEG成功地区分了这些过程。
结果支持了在单词识别过程中早期进行语音处理，随后是语音和语义处理交互的预测。这些过程的神经解剖学位点与先前的神经心理学和功能磁共振成像研究一致。结果也对将类似N400的反应作为语义处理标记的经典解释有影响。
