Brain plasticity and language learning

大脑可塑性和语言学习

• 批准号: RGPIN-2014-05371
• 负责人: Klein, Denise
• 金额: $ 1.89万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=631346
• 关键词: Brain; plasticity; language; learning

A fundamental question in cognitive neuroscience is how the brain’s language-processing system develops and how it is affected by early language learning experiences. The work proposed takes advantage of natural linguistic situations to explore issues related to brain plasticity and language development, and combines high resolution structural and functional brain-imaging with behavioural testing. We propose four experiments in different language learners of Quebec that focus on persistence and attrition of language circuits related to early language-learning experience. Experiment 1 examines the neural basis of speech perception in simultaneous bilinguals (two languages from birth and highly proficient in both), sequential bilinguals (one language early and one language after age 5 years and highly proficient in both) and monolinguals (proficient in one language). Here we hypothesize that exposure to two languages from birth may allow a different structuring of perceptual space and, hence, a different neural organization from that observed in late L2 learners and, even more so, from that of monolingual speakers. Experiment 2 examines the nature of neural change related to intensive language training and how this impacts speech perception. Here we test the hypothesis that the perceptual window will be closed to learning new categories for late learners. Experiment 3 assesses whether training of these learner groups on a novel phonetic learning task (the Hindi dental-retroflex) will provide an advantage to those with earlier exposure to two language systems as compared to one, with the prediction that early perceptual structuring may generalize to new language-learning situations. We predict that early specialization with two sound-systems will permit generalization to novel patterns. Finally, in Experiment 4, we address the question as to whether, after abrupt loss of a language in infancy, the neural circuits still remain plastic, thus yielding an advantage to these speakers in the re-acquisition of this “first” language later in life, or whether these circuits are overwritten by another language experience, without providing any early advantage. Because it is thought that that the laying down of sound patterns is a process that potentially occurs during an optimal period early in development, the input received during this time may be crucial in understanding language abilities later in life. The program of research addresses the extent to which the human brain has the capacity to change as a result of language learning; that is, the extent to which neural patterns are fixed and the extent to which these patterns can be altered later in life. This work has strength in that we examine very specific changes in behavior, to make a link with how the brain changes through enhanced language learning, while concurrently examining the factors that contribute to more rapid or more successful learning in our individual participants. The results from these studies should confirm that neuroplasticity related to speech perceptual circuits can be observed even in adult brains and should shed light on how the brain changes in response to training. The proposed studies should help reveal the neural underpinnings of brain development in relation to age of language exposure and as such could lead to advances in language-education policies in Canada.

认知神经科学的一个基本问题是大脑的语言处理系统如何发展以及它如何受到早期语言学习经历的影响。这项工作利用自然语言环境来探索与大脑可塑性和语言发展相关的问题，并将高分辨率结构和功能大脑成像与行为测试相结合。我们提出了针对魁北克不同语言学习者的四项实验，重点关注与早期语言学习经历相关的语言回路的持久性和消耗。实验 1 检查同时双语者（从出生时就掌握两种语言，并且对两种语言都高度熟练）、顺序双语者（早期一种语言，5 岁后一种语言，并且对两种语言都非常熟练）和单语者（精通一种语言）的语音感知的神经基础。在这里，我们假设从出生开始接触两种语言可能会产生不同的感知空间结构，因此会产生与晚期二语学习者观察到的不同的神经组织，甚至与单语使用者的神经组织不同。实验 2 检查与强化语言训练相关的神经变化的本质以及它如何影响言语感知。在这里，我们测试了这样的假设：对于晚期学习者来说，感知窗口将关闭以学习新类别。实验 3 评估了对这些学习者群体进行新的语音学习任务（印地语牙卷舌音）训练是否会给那些较早接触两种语言系统的人带来优势，并预测早期感知结构可能会推广到新的语言学习情境。我们预测，两个声音系统的早期专业化将允许推广到新的模式。最后，在实验 4 中，我们解决了这样的问题：在婴儿期突然丧失语言后，神经回路是否仍然保持可塑性，从而为这些说话者在以后的生活中重新习得这种“第一”语言带来优势，或者这些回路是否被另一种语言经验覆盖，而没有提供任何早期优势。因为人们认为声音模式的形成是一个可能发生在发育早期最佳时期的过程，所以在这段时间内收到的输入可能对于理解以后生活中的语言能力至关重要。该研究计划探讨了人类大脑因语言学习而发生变化的能力；也就是说，神经模式的固定程度以及这些模式在以后的生活中可以改变的程度。这项工作的优势在于，我们检查了非常具体的行为变化，通过增强语言学习与大脑如何变化建立联系，同时检查有助于个体参与者更快或更成功学习的因素。这些研究的结果应该证实，即使在成人大脑中也可以观察到与言语感知回路相关的神经可塑性，并且应该揭示大脑如何响应训练而变化。拟议的研究应有助于揭示与语言接触年龄相关的大脑发育的神经基础，因此可能会促进加拿大语言教育政策的进步。