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

健康成人的大脑在获得新技能（如学习说一门新语言）后，在整个生命周期中都保持着显著的结构和组织调整能力。这种现象被称为经验依赖的大脑可塑性。先前的研究表明，重复的发声活动，如表演、电视和广播，可以改变支持言语产生的大脑系统的神经组织。这样可以提高声音表现，比如更好地控制自己的声音和更精确的发音。然而，参与声乐专业知识发展的神经机制仍然知之甚少。该计划的目的是更好地了解健康的年轻人和老年人的非音乐声乐专业知识（例如电视和广播播音员，演员和口译员）的神经生物学相关性。这一目标将通过使用各种方法的一系列研究来解决，包括脑刺激、磁共振成像（MRI）和与可塑性相关的生物化合物的测量，如谷氨酸和BDNF。在第一个实验中，我们将使用分子和MRI技术研究具有不同声乐专业知识水平的健康年轻人和老年人的大脑，并将其与没有声乐专业知识的健康年轻人和老年人的大脑进行比较。在随后的研究中，我们将刺激年轻人和老年人的大脑的不同部位，以检查刺激对声音控制和大脑化学的影响。由于大脑刺激技术尚未优化用于声乐专业知识的研究，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，这很重要，因为众所周知，可塑性的能力会随着年龄的增长而下降。利用这些研究产生的知识，我们将进行一项结合分子、MRI和脑刺激方法的声乐训练研究，研究声乐经验引起的可塑性。我们将招募三组没有声乐专业知识的健康成年人，对他们进行为期4周的训练，每周两次，使用声音控制，语速和发音练习相结合的方法。其中一组将只接受培训。另一组只接受脑部刺激。第三组将两者都得到。通过分子和核磁共振技术的测量，研究人员预计，同时接受这两种训练的那一组将在行为上（更好的声乐表现）和大脑中表现出最明显的声乐学习能力。这一研究项目将推进健康衰老人类大脑中经验诱导的可塑性机制的现有知识。这些知识将有助于大脑增强技术、认知训练和认知刺激应用的发展，这些技术正在世界各地开发并获得专利。

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. This phenomenon is known as experience-dependent brain plasticity. Prior studies have suggested that repeated vocal activities, such as acting and television and radio broadcasting, can modify the neural organization of the brain systems that supports speech production. This results in enhanced vocal performance such as a better control of one's voice and more precise articulation. However, the neural mechanisms involved in the development of vocal expertise are still poorly understood. The objective of this program is to better understand the neurobiological correlates of non-musical vocal expertise (e.g. in television and radio broadcasters, actors and interpreters) in healthy young and older adults. This objective will be addressed via a series of studies using various methods including brain stimulation, magnetic resonance imaging (MRI) and measurements of biological compounds that have been associated with plasticity, such as glutamate and BDNF. In the first experiment, we will study the brain of healthy young and older adults with different levels of vocal expertise and compare it to the brain of healthy young and older adults with no vocal expertise, using molecular and MRI techniques. In subsequent studies, we will stimulate different parts of the brains of young and older non-experts to examine the effect that stimulation has on vocal control and brain chemistry. Because brain stimulation technologies are not yet optimized for the study of vocal expertise, 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, which is important because the capacity for plasticity is known to decline with age. Using the knowledge generated in these studies, we will conduct a vocal training study combining molecular, MRI and brain stimulation methods to study plasticity induced by vocal experience. We will recruit three groups of healthy adults with no vocal expertise and train them for 4 weeks, twice a week, using a combination of vocal control, speech rate and articulation exercises. One of the groups will receive only the training. The other group will receive only brain stimulation. The third group will receive both. It is expected that the group receiving both will show the most evidence of vocal learning, behaviourally (better vocal performance) and in the brain, measured with molecular and MRI techniques. This research program will advance current knowledge of experience-induced plasticity mechanisms in the healthy aging human brain. This knowledge will contribute to the development of brain-enhancing technologies, cognitive training and cognitive stimulation applications, which are being developed and patented across the world.