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

在获得新技能后，健康的成年人的大脑在整个生命周期中保持着非凡的能力来修改其结构和组织，比如学习一种新的语言。这种现象被称为经验依赖型大脑可塑性。先前的研究表明，反复发声活动，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。这导致了增强的声乐表演，例如更好地控制一个人的声音和更精确的发音。然而，涉及发声技能发展的神经机制仍然知之甚少。这个项目的目的是为了更好地了解健康的年轻人和老年人的非音乐发声技能(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进行的一系列研究来实现，包括脑刺激、磁共振成像(MRI)和与可塑性有关的生物化合物的测量，如谷氨酸和BDNF。在第一个实验中，我们将研究具有不同发声专长的健康年轻人和老年人的大脑，并使用分子和核磁共振技术将其与没有发声专长的健康年轻人和老年人的大脑进行比较。在随后的研究中，我们将刺激年轻的和年长的非专家的大脑的不同部分，以检查刺激对发声控制和大脑化学的影响。由于脑刺激技术尚未针对发声专业知识的研究进行优化，因此我们将测试诱导语音系统可塑性的不同方案，并确定在年轻人和老年人中产生最显著变化的方案，这一点很重要，因为可塑性能力已知会随着年龄的增长而下降。利用这些研究中产生的知识，我们将进行一项结合分子、磁共振和脑刺激方法的发声训练研究，以研究发声经验诱导的可塑性。我们将招募三组没有发声专长的健康成年人，并对他们进行为期4周的训练，每周两次，结合发声控制、语速和发音练习。其中一组将只接受培训。另一组将只接受大脑刺激。第三组将同时获得这两项服务。预计通过分子和核磁共振技术测量，接受这两种方法的那组人将在行为上(更好的发声表现)和大脑中表现出最多的声乐学习证据。这项研究计划将促进对健康老化人脑中经验诱导的可塑性机制的现有知识。这些知识将有助于开发大脑增强技术、认知训练和认知刺激应用，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.