Somatosensory Basis of Human Motor Learning

我研究的长期目标是了解人类中枢神经系统是如何产生自主运动和运动学习的。这里描述的研究项目的目标是测试运动学习不仅涉及运动行为和大脑运动区域的变化，还包括体感功能和体感神经处理的变化。运动学习不仅改变了我们的运动方式，还改变了我们处理和感知自己运动的方式。5年的目标是：(1)测试当我们学习与环境中的物体互动时，体感知觉以系统的方式变化的想法，以及(2)测试这些影响在体感和运动脑区域的神经基础。我们将测试基于学习的躯体感觉变化将取决于物体是目标（要达到的东西）还是障碍的想法。我们将测试一个假设，即当物体有障碍物时，与没有物体时相比，感知到的手的位置会从物体移向目标。我们将测试体感敏锐度在障碍物附近更强，而在目标附近更弱的想法。有趣的是，在语音感知中，听众对靠近元音原型（语音目标）的元音的声学差异不太敏感，而远离原型的元音（感知磁体效应）则不太敏感。这提出了一种有趣的可能性，即感知空间的扭曲是一种与熟练运动行为相关的普遍现象。我们还将测试皮层和节段性（脊柱）对伴随运动学习的体感觉变化的贡献。我们将使用重复经颅磁刺激（rTMS）来探讨在运动学习前后涉及体感觉、动作和运动学习的几个皮质区域的作用，包括初级体感觉皮质区SI和SII，辅助运动区（SMA），背侧和腹侧运动前皮质区PMd和PMv，以及顶叶皮质区。为了评估节段性反射调节的潜在作用，我们将使用h反射范式来评估运动学习前后反射兴奋性的变化，以及这些变化如何与感觉肢体位置的变化相关。总之，行为学、神经生理学和神经影像学研究中越来越多的证据表明，运动技能的习得涉及感知和运动学习。运动学习改变了感知功能和大脑的感觉回路。这为运动学习提供了一种新的理论途径，其中知觉学习和感觉可塑性起着重要作用。更好地理解运动技能学习的感觉和运动决定因素，可能会导致更好的脑机接口，如神经假肢，以及建立具有生物启发控制的拟人机器人的新方法。

The long term goal of my research is to understand how the human central nervous system produces voluntary movement and motor learning. The goal of the research program described here is to test the idea that motor learning involves not only changes to motor behaviour and motor areas of the brain, but incorporates changes in somatosensory function and somatosensory neural processing as well. Motor learning changes not only how we move but how we process and perceive our own movements. The 5-yr objectives are (1) to test the idea that somatosensory perception changes in systematic ways when we learn to interact with objects in the environment, and (2) to test the neural basis of these effects in somatosensory and motor brain areas. We will test the idea that learning-based somatosensory changes will depend on whether an object is a target (something to be reached) or an obstacle. We will test the hypothesis that sensed hand position will shift away from an object when it is an obstacle, and towards targets, compared to when there is no object. We will test the idea that somatosensory acuity will be greater near obstacles, and less near targets. Interestingly, in speech perception, listeners are less sentitive to acoustic differences in vowels that sit close to a vowel prototype (a speech target) compared to those that sit farther away from the prototype (the perceptual magnet effect). This raises the interesting possibility that warping of perceptual space is a general phenomenon associated with skilled motor behaviour. We will also test the cortical and segmental (spinal) contributions to somatosensory change accompanying motor learning. We will use repetitive transcranial magnetic stimulation (rTMS) to probe the role of several cortical areas involved in somatosensation, action and motor learning, before and after motor learning, including primary somatosensory cortical areas SI and SII, supplementary motor area (SMA), dorsal and ventral premotor cortices PMd and PMv, and parietal cortical areas. To assess the potential role of segmental reflex modulation we will use an H-reflex paradigm to assess changes in reflex excitability before vs after motor learning, and how those changes correlate with changes in sensed limb position. In summary, there is accumulating evidence from behavioral, neurophysiological, and neuroimaging studies that the acquisition of motor skills involves both perceptual and motor learning. Motor learning changes perceptual function and the sensory circuits of the brain. This points to a new theoretical approach to motor learning in which perceptual learning and sensory plasticity play a fundamental role. A better understanding of the sensory as well as motor determinants of motor skill learning could lead to better brain-machine interfaces such as neuro-prosthetic arms, as well as new approaches to building anthropomorphic robots with biologically-inspired control.