Multimodal Sensory Modulation and Human Motor Control

为了在日常活动中与我们的环境相互作用，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感觉信息。这种处理对于准确控制运动、学习导致大脑适应的新运动技能以及成功地重新学习脑损伤后的运动模式是必不可少的。感觉输入最初到达，并在大脑中非常不同的、特定于通道的区域(皮质)进行处理，然后整合到更高级别的感觉关联皮质区域。以前的研究已经提供了关于特定通道中的感觉输入如何在相对早期的皮层水平上在运动中被呈现的详细机制信息。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处理的最早阶段，即初级体感皮质，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、无人注意的信息的早期皮质表征，而促进与任务相关的有人注意的信息。控制这一选择的具体区域尚不清楚，但包括前额叶和顶叶皮质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发挥了重要作用。当中枢神经系统被呈现给多种来源的感觉输入时，这些控制机制是如何改变的，我们知道的要少得多，这在自然运动中通常是这样的。我们目前的工作表明，竞争性视觉和触觉(触觉)输入的大脑皮层表征实质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大脑皮层水平上发展对来自多种形式(视觉、肢体位置感觉、触觉)的感觉输入的相互作用和整合的基本了解，以及这在获得和控制正常肢体运动中所起的作用。提出了三个研究主题，包括研究神经机制的实验：(1)在多个感觉输入中选择相关刺激，(2)相关多模式刺激的整合，以及(3)大脑中经验依赖的适应。研究计划中的实验主题将为几名学员提供重要的培训机会，包括使用先进的人类电生理技术来研究感觉运动功能。该提案将为潜在的战略提供信息，这些战略可以增强大脑的动态适应能力，以改善健康个体的运动表现，并加强康复策略，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.