Mechanisms of experience-induced brain plasticity in the adult speech system

说话是一种非常复杂的人类行为，我们对它的神经结构还只是部分了解。尽管在理解神经语言系统方面取得了巨大的进步，但关于该系统的组织，它与语言表现的关系，以及更重要的是，它在成人寿命中的进化，仍然存在几个问题。尽管正常的结构和功能随着年龄的增长而下降，健康的成年人的大脑在获得新技能（如学习说一门新语言或演奏一种新乐器）后，在整个生命周期中都保持着改变其结构和组织的非凡能力。这种现象被称为经验依赖的大脑可塑性。除了技能学习之外，另一种诱导大脑可塑性的方法是通过使用一种名为“重复经颅磁刺激”（rTMS）的设备。rTMS向特定的大脑区域提供磁刺激，可以改变它们的功能，从而增强行为。这个研究项目的目的是通过研究年龄和不同的经历如何改变语言系统的解剖结构和功能来更好地理解成人语言系统的神经生物学。为了实现这一总体目标，将进行一系列研究。第一组研究将侧重于优化rTMS协议，通过诱导语音系统不同区域的可塑性来增强语音产生。由于大脑刺激技术尚未优化用于言语研究，我们将测试不同的方案来诱导言语系统的可塑性，并确定在年轻人和老年人中产生最显著变化的方案。利用这些研究中产生的知识，我们将进行纵向语音训练研究，包括学习产生和感知新的语音。将招募三组健康成年人。一组只接受语言训练。第二组只接受rTMS。第三组将两者都得到。研究人员预计，同时接受rTMS和语言训练的那组人在行为（增强的语言表现）和大脑（用磁共振成像（MRI）测量）方面表现出最明显的可塑性。行为和核磁共振测量将在训练开始时、4周后和8周后进行，使我们能够检查行为和大脑变化的时间过程。这一研究项目将推进健康人类大脑中经验诱导的可塑性机制的现有知识。该计划还将对神经语音系统的理论和知识做出重大贡献。最后，作为该计划的一部分产生的知识将有助于大脑增强技术和认知刺激应用的发展，这些技术在缺乏足够的科学和理论支持的情况下正在世界各地开发和申请专利。

Speaking is a remarkably complex human action whose neural architecture is still only partly understood. Despite tremendous progress in understanding the neural speech system, several questions remain regarding the organization of this system, its relationship to speech performance, and, importantly, its evolution over the adult lifespan. Despite a normal decline of structure and functions with age, the healthy adult brain retains a remarkable capacity to modify its structure and organization across the entire lifespan, following the acquisition of new skills, such as learning to speak a new language or to play a new instrument. This phenomenon is known as experience-dependent brain plasticity. In addition to skill learning, another method to induce brain plasticity is through the use of a device called "repetitive transcranial magnetic stimulation" or rTMS. rTMS delivers magnetic stimulation to specific brain areas and can modify their functioning, which can enhance behaviour. The objective of this research program is to better understand the neurobiology of the adult speech system by investigating how age and different kinds of experience can change the anatomy and functioning of the speech system. To achieve this general objective, a series of studies will be conducted. The first set of studies will focus on optimizing a rTMS protocol to enhance speech production by inducing plasticity in different regions of the speech system. Because brain stimulation technologies are not yet optimized for the study of speech, we will test different protocols for inducing plasticity in the speech system and identify the one that produces the most significant changes in younger and older adults. Using the knowledge generated in these studies, we will conduct a longitudinal speech training study consisting in learning to produce and perceive new speech sounds. Three groups of healthy adults will be recruited. One group will receive only the speech training. The second group will receive only rTMS. The third group will receive both. It is expected that the group receiving both rTMS and the speech training will show the most evidence of plasticity, behaviourally (enhanced speech performance) and in the brain, measured using magnetic resonance imaging (MRI). Behavioural and MRI measurements will be made at the beginning of the training, after 4 weeks and after 8 weeks, allowing us to examine the time course of behavioural and brain changes. This research program will advance current knowledge of experience-induced plasticity mechanisms in the healthy human brain. The proposed program will also contribute significantly to theories and knowledge about the neural speech system. Finally, the knowledge generated as part of the program will contribute to the development of brain-enhancing technologies and cognitive stimulation applications, which are being developed and patented across the world in the absence of adequate scientific and theoretical support.