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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=655721
• 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.

认知神经科学中的一个基本问题是大脑的语言处理系统是如何发展的，以及它是如何受到早期语言学习经验的影响的。这项建议的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脑成像与行为测试相结合。我们在魁北克不同的语言学习者中提出了四个实验，重点关注与早期语言学习经验相关的语言回路的持久性和磨损性。实验1考察了双语者(两种语言从出生起就精通两种语言)、顺序式双语者(早期一种语言，5岁以后一种语言，两种语言都非常熟练)和单语者(精通一种语言)的言语感知的神经基础。这里我们假设，从出生起接触两种语言可能会导致感知空间的结构不同，因此，与第二语言学习者晚期观察到的不同的神经组织，更不同于只说一种语言的人的神经组织。实验2考察了与强化语言训练有关的神经变化的性质，以及这种变化如何影响言语感知。在这里，我们检验了一种假设，即对于学习迟缓的学习者来说，感知窗口将关闭，以学习新的类别。实验3评估了对这些学习者进行一项新的语音学习任务(印地语牙齿卷曲)的训练是否会为那些较早接触两种语言系统的人提供相对于一种语言系统的优势，并预测早期知觉结构可能会概括为新的语言学习情景。我们预测，两个音响系统的早期专门化将允许推广到新的模式。最后，在实验4中，我们讨论了这样一个问题：在婴儿时期突然失去一种语言后，神经回路是否仍然是可塑性的，从而在以后的生活中重新获得这一“第一”语言时对这些说话者产生了优势，或者这些回路是否被另一种语言经验所覆盖，而没有提供任何早期优势。因为人们认为，语音模式的形成是一个可能发生在发展早期的最佳时期的过程，所以在这一时期接受的输入可能对后来的生活中理解语言能力至关重要。该研究项目致力于解决人类大脑因语言学习而发生变化的程度；即，神经模式在多大程度上是固定的，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，我们研究了非常具体的行为变化，以与大脑如何通过增强语言学习而变化联系起来，同时研究了有助于我们的个体参与者更快或更成功地学习的因素。这些研究的结果应该会证实，即使在成年人的大脑中也可以观察到与言语知觉回路相关的神经可塑性，并应该有助于揭示大脑对训练的反应方式。拟议的研究应该有助于揭示大脑发育与语言接触年龄相关的神经基础，因此可能导致加拿大语言教育政策的进步。