Sensory contributions to control of human hand movements: digit representations in higher-order somatic loci and their neural interactions with primary motor cortex

拟议中的研究将调查人脑中处理与手有关的感觉和运动信息的区域。感兴趣的区域包括初级和次级体感觉皮层和内侧顶叶上小叶。目的是了解这些皮层区域如何代表感觉输入，以及当输入对任务变得重要或指示即将到来的手部运动时，它们的表现是如何变化的。目标将通过两种提供互补信息的非侵入性技术，功能性磁共振成像（fMRI）和配对脉冲经颅磁刺激（TMS）来实现。对于每个感兴趣的区域，功能磁共振成像将用于识别哪些手指占据了最多的皮质区域，对特定类型的感觉输入的反应有多强烈，以及反应是增加还是减少取决于输入与任务或运动的相关性。使用经颅磁刺激，每个感兴趣的区域和初级运动皮层之间的相互作用将被探索，初级运动皮层是负责手部运动的脊髓路径的最大贡献者。每个感兴趣的皮质区域都与初级运动皮层有直接的投射，但是感觉区域何时向初级运动皮层传递信息以及如何传递信息还不确定。例如，感觉投射会减少初级运动皮层的反应，还是会增加反应？了解支撑感觉引导手部运动的神经机制，对于开发旨在改善中风或运动障碍（如肌张力障碍）患者手部功能的疗法至关重要。该研究计划将调查健康人群手部感觉运动的皮质机制，这是开发帮助临床人群的方法的先驱。

The proposed research will investigate the areas of the human brain that process both sensory and movement information related to the hand. The areas of interest include the primary and secondary somatosensory cortex and the medial superior parietal lobule. The goals are to understand how each of these cortical areas represent sensory input, and how their representations change when input becomes important to the task, or dictates an upcoming movement of the hand. The goals will be accomplished using two non-invasive techniques that provide complimentary information, functional magnetic resonance imaging (fMRI) and paired-pulse transcranial magnetic stimulation (TMS). For each area of interest, fMRI will be used to identify which digits occupy the most cortical territory, how intense responses are to specific types of sensory input, and if responses increase or decrease depending on how relevant the input is to the task, or movement. Using TMS, the interaction between each area of interest and the primary motor cortex, the largest contributor to the spinal path responsible for hand movements, will be probed. Each of the cortical areas of interest have direct projections with the primary motor cortex yet there are uncertainties about when the sensory area conveys its information to the primary motor cortex, and how this information is conveyed. For example, will the sensory projection reduce responses in primary motor cortex, or will it increase responses? Understanding the neural mechanisms that underpin sensory-guided hand movements is essential to developing therapies that aim to improve hand function in patients such as those have suffered stroke or with movement disorders such as dystonia. The proposed research program will investigate the cortical mechanisms of sensory-motor hand movement in healthy populations, a precursor to developing methods to assist clinical populations.