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，其神经结构仍然只有部分了解。尽管在理解神经言语系统方面取得了巨大进展，但关于该系统的组织，其与言语表现的关系，以及重要的是，其在成人寿命中的演变，仍然存在一些问题。尽管随着年龄的增长，大脑的结构和功能会正常下降，但健康的成年人在获得新技能（如学习说一种新语言或演奏一种新乐器）后，在整个生命周期中仍然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性大脑可塑性。除了技能学习，另一种诱导大脑可塑性的方法是使用一种称为“重复经颅磁刺激”或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。 这项研究计划的目的是通过调查年龄和不同类型的经验如何改变语音系统的解剖和功能，以更好地了解成人语音系统的神经生物学。为了实现这一总体目标，将进行一系列研究。第一组研究将专注于优化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语音研究，我们将测试不同的方案来诱导语音系统的可塑性，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，我们将进行一项纵向语音训练研究，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。第二组仅接受rTMS。第三组将获得两者。预计接受rTMS和言语训练的组将在行为上（增强的言语表现）和大脑中显示出最多的可塑性证据，使用磁共振成像（MRI）进行测量。 行为和MRI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。这项研究计划将推进健康人脑中经验诱导的可塑性机制的现有知识。该计划也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开发大脑增强技术和认知刺激应用，这些技术和应用正在世界各地开发，并在缺乏足够的科学和理论支持的情况下获得专利。

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.