University of Connecticut & Haskins Laboratories, United States.
Yale University & Haskins Laboratories, United States.
Neuropsychologia. 2018 Mar;111:133-144. doi: 10.1016/j.neuropsychologia.2018.01.011. Epub 2018 Jan 31.
Word learning depends not only on efficient online binding of phonological, orthographic and lexical information, but also on consolidation of new word representations into permanent lexical memory. Work on word learning under a variety of contexts indicates that reading and language skill impact facility of word learning in both print and speech. In addition, recent research finds that individuals with language impairments show deficits in both initial word form learning and in maintaining newly learned representations over time, implicating mechanisms associated with maintenance that may be driven by deficits in overnight consolidation. Although several recent studies have explored the neural bases of overnight consolidation of newly learned words, no extant work has examined individual differences in overnight consolidation at the neural level. The current study addresses this gap in the literature by investigating how individual differences in reading and language skills modulate patterns of neural activation associated with newly learned words following a period of overnight consolidation. Specifically, a community sample of adolescents and young adults with significant variability in reading and oral language (vocabulary) ability were trained on two spoken artificial lexicons, one in the evening on the day before fMRI scanning and one in the morning just prior to scanning. Comparisons of activation between words that were trained and consolidated vs. those that were trained but not consolidated revealed increased cortical activation in a number of language associated and memory associated regions. In addition, individual differences in age, reading skill and vocabulary modulated learning rate in our artificial lexicon learning task and the size of the cortical consolidation effect in the precuneus/posterior cingulate, such that older readers and more skilled readers had larger cortical consolidation effects in this learning-critical region. These findings suggest that age (even into late adolescence) and reading and language skills are important individual differences that affect overnight consolidation of newly learned words. These findings have significant implications for understanding reading and language disorders and should inform pedagogical models.
词汇学习不仅依赖于语音、拼写和词汇信息的有效在线结合，还依赖于将新单词的表示形式整合到永久词汇记忆中。在各种语境下进行的词汇学习工作表明，阅读和语言技能会影响印刷品和语音中词汇学习的便利性。此外，最近的研究发现，语言障碍个体在初始单词形式学习和随时间保持新学习的表示形式方面存在缺陷，这暗示了与维持相关的机制可能是由夜间巩固缺陷驱动的。尽管最近有几项研究探讨了新学习单词的夜间巩固的神经基础，但目前尚无研究在神经水平上检查夜间巩固的个体差异。本研究通过调查阅读和语言技能的个体差异如何调节与新学习单词相关的神经激活模式，来解决文献中的这一空白。具体来说，对具有阅读和口语语言（词汇）能力显著差异的青少年和年轻成年人的社区样本进行了两项口语人工词汇的训练，一项在 fMRI 扫描前一天晚上进行，另一项在扫描前早上进行。在训练和巩固的单词与仅训练但未巩固的单词之间进行激活比较，结果显示在许多与语言和记忆相关的区域中，皮质激活增加。此外，年龄、阅读技能和词汇量的个体差异调节了我们的人工词汇学习任务中的学习率以及在楔前叶/后扣带回中的皮质巩固效应的大小，即年龄较大的读者和技能较高的读者在这个学习关键区域中的皮质巩固效应更大。这些发现表明，年龄（甚至进入青春期后期）和阅读及语言技能是影响新学习单词的夜间巩固的重要个体差异。这些发现对理解阅读和语言障碍具有重要意义，并应告知教学模型。
