Soman Akshara, Ramachandran Prathibha, Ganapathy Sriram
Learning and Extraction of Acoustic Patterns Lab, Indian Institute of Science, Bangalore, India.
Front Neurosci. 2022 Mar 3;16:763324. doi: 10.3389/fnins.2022.763324. eCollection 2022.
The event-related potential (ERP) of electroencephalography (EEG) signals has been well studied in the case of native language speech comprehension using semantically matched and mis-matched end-words. The presence of semantic incongruity in the audio stimulus elicits a N400 component in the ERP waveform. However, it is unclear whether the semantic dissimilarity effects in ERP also appear for foreign language words that were learned in a rapid language learning task. In this study, we introduced the semantics of Japanese words to subjects who had no prior exposure to Japanese language. Following this language learning task, we performed ERP analysis using English sentences of semantically matched and mis-matched nature where the end-words were replaced with their Japanese counterparts. The ERP analysis revealed that, even with a short learning cycle, the semantically matched and mis-matched end-words elicited different EEG patterns (similar to the native language case). However, the patterns seen for the newly learnt word stimuli showed the presence of P600 component (delayed and opposite in polarity to those seen in the known language). A topographical analysis revealed that P600 responses were pre-dominantly observed in the parietal region and in the left hemisphere. The absence of N400 component in this rapid learning task can be considered as evidence for its association with long-term memory processing. Further, the ERP waveform for the Japanese end-words, prior to semantic learning, showed a P3a component owing to the subject's reaction to a novel stimulus. These differences were more pronounced in the centro-parietal scalp electrodes.
在使用语义匹配和不匹配的结尾词进行母语语音理解的情况下，脑电图（EEG）信号的事件相关电位（ERP）已得到充分研究。音频刺激中语义不一致的存在会在ERP波形中引发N400成分。然而，对于在快速语言学习任务中学习的外语单词，ERP中的语义差异效应是否也会出现尚不清楚。在本研究中，我们向从未接触过日语的受试者介绍了日语单词的语义。在这个语言学习任务之后，我们使用语义匹配和不匹配的英语句子进行ERP分析，其中结尾词被其日语对应词替换。ERP分析表明，即使学习周期很短，语义匹配和不匹配的结尾词也会引发不同的脑电模式（类似于母语情况）。然而，新学单词刺激所呈现的模式显示出P600成分的存在（极性与已知语言中所见的相反且延迟）。地形分析表明，P600反应主要出现在顶叶区域和左半球。在这个快速学习任务中没有N400成分，可以被视为其与长期记忆处理相关的证据。此外，在语义学习之前，日语结尾词的ERP波形由于受试者对新刺激的反应而显示出P3a成分。这些差异在中央顶叶头皮电极上更为明显。
