Uncovering the cortical architecture of motor skill

从弹钢琴到扣衬衫--熟练的手部动作对几乎每一项人类活动都是必不可少的。这个研究项目的主要目标是了解人脑是如何学习和产生复杂动作的。当我们发展运动技能的专业技能时，我们的大脑会发生什么变化？目前的一些理论认为，整个运动模式(如网球发球)在神经元(或神经细胞)之间的连接中根深蒂固，就像歌曲存储在唱片中的方式一样。然而，运动专家可以灵活地结合较小的运动元素来产生新的运动，比如钢琴家在著名的旋律上即兴演奏，这表明了一种不同的架构。我们的假设是，主要运动区学习基本运动元素，而次要运动区存储更抽象的表征，然后激活更简单的运动基元序列。为了测试这种神经表征，我们将使用一种名为功能磁共振成像(FMRI)的技术来观察人类志愿者在执行不同运动任务时大脑中的活动。我们不只是研究大脑的哪些部分被激活，而是研究这些区域内的细粒度活动模式。通过观察不同动作的活动模式之间的关系，我们可以了解这些动作是如何表现的，即大脑区域是否反映了单一的动作元素、关于执行的具体细节，或者它们是否代表了更抽象的特征。发现人类大脑中这种表征的能力使我们能够了解运动技能专家(如音乐家或运动员)的大脑与新手的大脑有何不同；帮助我们评估和改进训练方案；并有助于理解中风后运动功能的恢复，在某种程度上，这涉及到与最初的运动技能学习类似的过程。该研究项目还将为为什么以及如何在运动练习中向大脑施加小电流(一种名为经颅直流电刺激的技术)能够改善健康人类的技能学习提供新的见解。

From playing the piano to buttoning a shirt – skilled hand movements are essential to nearly every human activity. The main objective of this research program is to understand how the human brain learns and produces complex movements. What changes in our brains as we develop expertise in a motor skill? Some current theories propose that whole movement patterns (such as a tennis serve) become engrained in the connections between neurons (or nerve cells), much like the way in which a song is stored on a record. However, the flexibility with which motor experts can combine smaller movement elements to produce a novel movement, such as a pianist improvising on a well-known melody, suggest a different architecture. Our hypothesis is that primary motor areas learn elementary movement elements, whereas secondary motor areas store a more abstract representation that then activates sequences of simpler movement primitives. To test for such neural representations, we will observe the activity in the brains of human volunteers, using a technique called functional magnetic resonance imaging (fMRI), while they perform different movement tasks. Instead of just studying which parts of the brain are activated, we investigate the fine-grained patterns of activity within of these areas. By looking at the relationship between the activity patterns for different movements, we can learn how these movements are represented, i.e., whether the brain areas reflect single movement elements, specific details about the execution, or whether they represent more abstract characteristics. The ability to uncover such representations in the human brain allows us to understand how the brains of motor skill experts, such as musicians or athletes, differ from novices; helps us to evaluate and improve training protocols; and aids in understanding the recovery of motor function after stroke, which to some degree involves similar processes as initial motor skill learning. The research program will also provide new insights into why and how a small electric current applied to the brain during motor practice (a technique called transcranial direct current stimulation) is able to improve skill learning in healthy humans.