Multimodal Sensory Modulation and Human Motor Control

为了在日常活动中与我们的环境进行互动，中枢神经系统（CNS）必须从来自许多来源的大量并发输入中识别和提取相关的感觉信息。这种处理对于精确控制运动，学习新的运动技能导致大脑适应，以及在脑损伤后成功重新学习运动模式至关重要。感觉输入最初到达并在大脑中非常不同的特定模式区域（皮层）进行处理，然后在高阶感觉关联皮层区域进行整合。先前的研究已经提供了详细的机制信息，说明了在相对早期的皮层水平上，特定模态内的感觉输入是如何在运动过程中被表征的。例如，我们正在进行的研究表明，体感信息的选择开始发生在皮层加工的最早阶段，即初级体感皮层，在感觉引导的运动和知觉辨别期间。高度选择性的机制似乎参与其中，包括抑制与任务无关的、未被注意的信息的早期皮层表征，促进与任务相关的、被注意的信息。控制这种选择的特定区域尚不清楚，然而，包括前额叶和顶叶皮层以及丘脑和小脑在内的多个大脑区域之间的相互作用似乎起着重要作用。当中枢神经系统受到多种感觉输入时，这些控制机制是如何改变的，就像在自然运动中通常发生的情况一样，人们对这一点知之甚少。我们目前的研究表明，竞争性视觉和触觉（触觉）输入的皮层表征在很大程度上取决于刺激之间的相关性和时间关系。因此，拟议的研究计划将侧重于在皮层水平上发展对来自多种方式（视觉，肢体位置感，触觉）的感觉输入的相互作用和整合的基本理解，以及这在正常肢体运动的获取和控制中所起的作用。提出了三个探究主题，包括实验研究(1)在多种感觉输入中选择相关刺激的神经机制，(2)相关多模态刺激的整合，以及(3)大脑中经验依赖的适应。本研究计划的实验主题将为几位受训者提供重要的训练机会，包括使用先进的人体电生理技术来研究感觉运动功能。该提案将为潜在的策略提供信息，可以增强大脑的动态适应，以改善健康个体的运动表现，加强康复策略，减少脑损伤后的残疾。

In order to interact in our environment during everyday activities, the central nervous system (CNS) must identify and extract relevant sensory information from a vast array of concurrent inputs from many sources. Such processing is essential for accurately controlling movements, learning new motor skills leading to adaptation in the brain, and successfully relearning movement patterns following brain injury. Sensory inputs initially arrive and are processed at very distinct, modality-specific areas of the brain (cortex) before being integrated in higher-order sensory association cortical areas. Previous research has provided detailed mechanistic information regarding how sensory inputs within a specific modality are represented during movement at a relatively early cortical level. For example, our ongoing research suggests that selection of somatosensory information begins to occur at the very earliest stage of cortical processing, the primary somatosensory cortex, during sensory-guided movement and perceptual discrimination. Highly selective mechanisms appear to be involved, including inhibition of early cortical representations of task-irrelevant, unattended information, with facilitation of task-relevant, attended information. The specific regions that control this selection are unclear, however interactions between multiple brain regions including the prefrontal and parietal cortex, as well as the thalamus and cerebellum appear to play an important role. Much less is known about how these mechanisms of control are altered when the CNS is presented with multiple sources of sensory inputs, as is usually the case during natural movement. Our current work suggests that the cortical representations of competitive visual and tactile (touch) input change substantially depending on the relevance and temporal relationship between the stimuli. As such the proposed research program will focus on developing fundamental understanding of the interactions and integration of sensory inputs from multiple modalities (vision, position sense of the limbs, touch) at a cortical level and the role this plays in the acquisition and control of normal limb movement. Three themes of inquiry are proposed that include experiments to study neural mechanisms of (1) selection of relevant stimuli among multiple sensory inputs, (2) integration of relevant multimodal stimuli, and (3) experience-dependent adaptations in the brain. The themes of experiments in the research program will provide important training opportunities for several trainees, including the use of advanced human electrophysiological technologies to study sensorimotor function. The proposal will inform potential strategies that can enhance the brain's dynamic adaptations to improve motor performance in healthy individuals and strengthen rehabilitation strategies and lessen disability following brain injury.