CORTICAL CONTROL OF ARM MOVEMENT UNDER PERTURBATIONS

描述（改编自申请人摘要）：研究者已 先前表明，记录的运动皮层的群体向量 神经元准确和连续地预测手臂轨迹， 意志运动 目前还不清楚这种预测信号与 用来移动手臂的肌肉收缩以及它如何相互作用 在控制臂运动中具有扰动。 如果出现意外 在动物的预期运动已经完成之后， 已经开始，运动轨迹会有偏差， 肌肉活动的反应性变化。 人们会期望看到 大脑皮层活动模式的变化 这种变化可能会逐渐演变 因为扰动变成运动的固定特征。 的 研究者们建议， 新的和适应的条件对扰动。 长期 本项目的目标是了解控制策略所使用的 感觉运动系统，因为它与环境， 意想不到的扰动。 目的是获取的信息 通过这项调查将有助于开发控制系统， 皮质信号控制神经机械假体或功能 用于脑/脊髓损伤患者的神经肌肉刺激系统 或其他神经损伤 所提出的方法涉及干扰灵长类动物手臂运动， 同时记录大脑皮层神经元的活动 通过长期植入的细线阵列电极， 渠道 恒河猴将被训练来执行一个3D的，不受限制的， 视觉引导中心->外展任务。 在每一次运动中， 调查人员将同时记录和关联手臂轨迹， 肌肉活动和皮层细胞活动。 他们将应用一个瞬变 通过在手腕处施加突然的拉力而对手臂造成的扰动 在运动开始后。 这种扰动将被应用于 在每次向八个伪随机呈现的 目标的 减小了摄动对机械臂轨迹的影响 因为动物知道扰动是任务的固定特征。 然后将消除扰动，以检查后效。 他们 将研究个体活动之间的时间关系， 皮质细胞及其群体载体、肌肉活动和终点 运动方向和速度，在扰动之前和之后。 这是通过比较四个不同阶段的数据来实现的。 实验：对照数据的训练阶段， 扰动首先被应用，适应阶段在动物已经 学习了扰动动力学和影响，以及灭绝阶段， 去除扰动。 在猴子适应了干扰之后， 他们希望看到一种预测策略在神经元和 在扰动开始之前的肌肉活动。 三维动态模型 的猴子手臂将被完善，并用于评估所采取的战略， 猴子来减少干扰的影响。

DESCRIPTION (Adapted from the Applicant's Abstract): The investigators have previously shown that the population vector of recorded motor cortical neurons predicts accurately and continuously the arm trajectory during a volitional movement. It is still unclear how this predictive signal relates to the muscle contractions used to move the arm and how it will interact with a perturbation in controlling arm movement. If an unexpected perturbation is applied to an animal s arm after its intended motion has already started, there will be deviations in movement trajectory and reactive changes in muscle activity. One would expect to see corresponding changes in the cortical activity patterns. This change may gradually evolve as the perturbation becomes a fixed feature of the movement. The investigators propose to examine this change in neuronal activities under both novel and adapted conditions toward the perturbation. The long term goal of this project is to understand control strategies used by the sensorimotor system as it interacts with an environment containing unexpected perturbations. The intent is that the information obtained through this investigation will help to develop control systems that utilize cortical signals to control neuromechanical prostheses or functional neuromuscular stimulation systems for humans with brain/spinal cord injury or other neurological damages. The proposed methodologies involve perturbing primate arm motions while simultaneously recording activities from a population of cortical neurons through a chronically implanted fine wire array electrode with up to 96 channels. Rhesus monkeys will be trained to perform a 3D, unrestrained, visually guided center->out reaching task. During each movement the investigators will simultaneously record and correlate arm trajectory, muscle activity and cortical cell activity. They will apply a transient perturbation to the arm by applying a sudden pulling force at the wrist after the initiation of the movement. This perturbation will be applied during every movement toward each of the eight pseudo-randomly presented targets. The effect of the perturbation on arm trajectory will be reduced as the animals learn that the perturbation is a fixed feature of the task. The perturbation will then be removed to examine the after-effects. They will examine the temporal relation among the activities of individual cortical cells and their population vectors, muscle activities, and endpoint movement directions and velocities, both before and after the perturbation. This is achieved by comparing data from four different phases of the experiment: the training phase for control data, the novel phase when the perturbation is first applied, the adaptation phase after the animals have learned the perturbation dynamics and effect, and the extinction phase upon removal of the perturbation. After the monkey adapts to the perturbations, they expect to see a predictive strategy demonstrated in the neuronal and muscle activity before the onset of the perturbation. The 3-D dynamic model of a monkey arm will be refined and used to evaluate strategies adopted by the monkey to minimize the effects of the perturbation.