Abstract：
Learning words in the mother tongue is a fundamental lifelong skill that involves complex cognitive and neural changes. In adults, newly learned words affect the organization of the lexical-semantic network and, compared to words that have been in the lexicon for longer, they activate the same cortical areas, but more extensively and/or intensively. It is however still unclear (1) which brain and cognitive processes underlying word production change when infrequent/unknown words are compared before and after learning and (2) whether integrating newly learned words impacts word specific processes or has a broader impact on unlearned words. The present study aims to investigate the electrophysiological changes underlying the production of rare words induced by learning and the effect of learning on an unlearned list of rare words belonging to the same semantic categories. To this end, 24 neurotypical adults learned one of two matched lists of 40 concrete rare words from 4 semantic categories. EEG (electroencephalographic) recordings were acquired during a referential word production task (picture naming) of the learned and unlearned words before and after the learning phase. The results show that the production of rare word is associated with event-related (ERP) differences between before and after learning in the period from 300 to 800 msec following the presentation of the imaged concept (picture). These differences consisted in a larger involvement of left temporal and parietal regions after learning between 300 and 400 msec i.e., the time window likely corresponding to lexical and phonological encoding processes. Crucially, the ERP changes are not restricted to the production of the learned rare words, but are also observed when participants try to retrieve words of a list of semantically and lexically matched rare words that they have not learned. The ERP changes on unlearned rare words are weaker and suggest that learning new words induces boarder effects also on unlearned words.
摘要：
用母语学习单词是一项基本的终身技能，涉及复杂的认知和神经变化。在成年人中,新学的单词会影响词汇语义网络的组织，与词汇中存在时间更长的单词相比，它们激活相同的皮质区域，但更广泛和/或更密集。然而，目前还不清楚(1)当学习前后比较不常见/未知单词时，单词产生的潜在大脑和认知过程会发生变化；(2)整合新学习的单词是否会影响单词特定过程或对未学习的单词产生更广泛的影响。本研究旨在研究由学习引起的稀有单词产生的电生理变化，以及学习对属于相同语义类别的稀有单词的未学习列表的影响。为此,24个神经典型的成年人从4个语义类别中学习了40个具体稀有单词的两个匹配列表之一。在学习阶段之前和之后，在学习和未学习的单词的参考单词产生任务（图片命名）期间获取EEG（脑电图）记录。结果表明，在呈现成像概念（图片）后的300至800毫秒的时间内，稀有词的产生与学习前后的事件相关（ERP）差异有关。这些差异包括在300和400毫秒之间学习后，左颞叶和顶叶区域更大的参与，即时间窗口可能对应于词汇和语音编码过程。至关重要的是，ERP的变化不仅限于学习的稀有单词的产生，但是当参与者尝试检索他们没有学过的语义和词汇匹配的稀有单词列表中的单词时，也会被观察到。未学习的稀有单词的ERP变化较弱，这表明学习新单词也会对未学习的单词产生边界效应。
