Sensory motor transformations in human cortex

摘要：该应用程序的长期目标是了解感觉的皮层处理 人类大脑皮层内的运动转换。必须进行大量的计算 执行以实现感觉引导的运动控制。在这些计算中脱颖而出的是视觉 行动目标的信息必须从视网膜的坐标转换为 用于运动的效应器的坐标，例如在视觉下到达的肢体坐标 环境中相互作用的指导和世界坐标。一旦抓住一个物体， 灵巧地操纵所抓取的物体需要来自手部的体感信号。内部 感觉运动通路内的模型对于估计身体和身体的当前状态至关重要 外部环境，考虑感觉反馈的滞后，并根据环境校准身体 环境。 我们将利用能够在临床中记录单个神经元群体的难得机会 旨在为因脊髓损伤而瘫痪的四肢瘫痪参与者开发神经假体的研究。 微电极阵列的皮层植入物将在感觉运动的三个关键位置进行 系统：初级运动皮层、初级体感皮层、后顶叶皮层。这些 微电极阵列可以实现记录和皮质内微刺激。 我们将测试体感和运动皮层代表想象中的手的假设 坐标，但后顶叶皮层是任务依赖性的，其群体神经活动可以灵活地 更改坐标系以对身体内的空间关系（手臂和眼睛）进行编码， 身体与世界之间（手臂和到达目标；相对于自我的物体）以及世界内部（相对 物体在世界中的位置）根据任务要求。皮质内诱发的知觉 微刺激和想象的感觉将被用来理解皮肤和 初级体感皮层和后顶叶皮层内的本体感觉信息。的 要测试的假设是想象的感觉和电诱发的感觉高度 重叠——不仅在初级体感皮层中，而且在后顶叶皮层中。最后，我们 假设人类的后顶叶皮层包含一个状态估计的内部模型 显示出自然行为和大脑控制行为的可塑性，并将这种学习转移到运动皮层。 这些研究不仅将极大地增进我们对人类感觉运动皮层回路的理解， 同时也将为未来神经假肢的设计提供基础知识。

Abstract: The long-term objective of this application is to understand cortical processing of sensory to motor transformations within the human cerebral cortex. A vast number of computations must be performed to achieve sensory-guided motor control. Standing out among these computations, visual information of the goals of action must be transformed from the coordinates of the retina to the coordinates of effectors used for movement, for instance limb coordinates for reaching under visual guidance and to world coordinates for interactions in the environment. Once an object is grasped, somatosensory signals from the hand are required for dexterous manipulation of grasped objects. Internal models within the sensory motor pathway are essential for estimating the current state of the body and the external environment, accounting for lags in sensory feedback, and calibrating the body to the environment. We will use the rare opportunity of being able to record from populations of single neurons in a clinical study designed to develop neural prosthetics for tetraplegic participants paralyzed by spinal cord injuries. Cortical implants of microelectrode arrays will be made within three key locations in the sensorimotor system: primary motor cortex, primary somatosensory cortex, and posterior parietal cortex. These microelectrode arrays enable both recording and intracortical microstimulation. We will test the hypothesis that somatosensory and motor cortex represent imagined reaches in hand coordinates, but posterior parietal cortex is task dependent, and its population neural activity can flexibly change coordinate frames to enable encoding of the spatial relations within the body (arm and eyes), between the body and world (arm and reach targets; objects relative to self), and within the world (relative position of objects in the world) as required by task demands. Percepts evoked by intracortical microstimulation and imagined sensations will be used to understand the representation of cutaneous and proprioceptive information within primary somatosensory cortex and posterior parietal cortex. The hypothesis to be tested is that imagined sensation and electrically evoked sensations are highly overlapping—not just in primary somatosensory cortex but also in posterior parietal cortex. Lastly, we hypothesize that the posterior parietal cortex contains in humans an internal model of state estimation that shows plasticity for both natural and brain-control behaviors and transfers this learning to motor cortex. These studies will not only greatly advance our understanding of the human sensorimotor cortical circuit, but also will provide basic knowledge for the design of future neural prosthetics.