Coding of Action by Motor & Premotor Cortical Ensembles

电机动作编码

基本信息

批准号：
10600020
负责人：
Nicholas G Hatsopoulos
金额：
$ 43.3万
依托单位：
UNIVERSITY OF CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-15 至 2025-03-31
项目状态：
未结题

项目摘要

Abstract The goal of this project is to understand how spatio-temporal patterns of activity across motor cortex initiate different types of voluntary movements. Large distributed ensembles of motor cortical neurons begin modulating their firing rates prior to voluntary movement and are thought to causally generate these movements. However, it is still unresolved why movement is not initiated when similar modulations in single unit motor cortical activity occur during movement planning, imagery, and visual observation of action. The amplitude of local field potential (LFP) oscillations in the beta frequency (15-40 Hz) range is known to attenuate prior to movement onset and is considered a mesoscopic signature of corticospinal excitability. We have recently discovered a sequential pattern of LFP beta attenuation and single unit modulation timing in primary motor cortex that is spatially organized prior to reaching movement onset but not during movement preparation. Our working hypothesis is that such a propagating sequential pattern is necessary to initiate movement. In this project, we will test and extend this hypothesis by demonstrating that such propagating patterns generalize to movement initiation of different behaviors including 2D reaching under different conditions, more complex 3D reach-to-grasp, and tongue protrusion and occur in premotor cortex. We will first demonstrate that propagating sequences in beta attenuation and single unit modulation timing occur during initiation of each of these behaviors along different portions of the somatotopic map of primary motor and premotor cortices. Second, we will provide a causal link between these propagating patterns and movement initiation by applying subthreshold, spatio-temporal patterns of electrical stimulation. We will demonstrate that movement initiation is delayed when patterned stimulation travels against the natural propagating sequence but not when it mimics the natural propagating pattern. Third, we will provide a mechanistic explanation of how these propagating sequences lead to muscle activation that supports movement initiation using patterned stimulus-triggered muscle activity and muscle decoding. To accomplish these aims, four high-density electrode arrays will be chronically implanted in the either the upper limb or orofacial areas of primary motor and premotor cortices from which 100s of single units and LFPs will be simultaneously recorded. A two-link exoskeletal robot and a motion tracking system using a set of fourteen infrared cameras will monitor the kinematics of the arm and hand. A strain gauge will measure tongue force and kinematics of the tongue will be tracked with a novel 3D x-ray fluoroscopy system. Indwelling EMG electrodes will also measure activity from arm, hand, and tongue muscles. A set of classical and novel computational methods will be employed to characterize the spatio-temporal dynamics of motor cortical activity during movement initiation.

抽象的该项目的目的是了解运动皮层跨越的时空活动模式如何不同类型的志愿运动。大型运动皮质神经元的分布式集合开始在自愿运动之前调节其发射率，并被认为是为此产生的动作。但是，仍然尚未解决，为什么当单一的类似调制时没有开始移动单位运动皮质活动在运动计划，图像和作用视觉观察过程中发生。这 beta频率（15-40 Hz）范围内局部场电位（LFP）振荡的幅度已知在运动开始之前，被认为是皮质脊髓兴奋性的介质特征。我们有最近发现了LFPβ衰减和单位调制时间的顺序模式运动皮层在运动开始之前是空间组织的，但在运动期间没有准备。我们的工作假设是，这种传播顺序模式对于启动是必要的移动。在这个项目中，我们将通过证明这种传播来检验和扩展这一假设模式推广到运动的运动开始，包括不同行为，包括2D到达不同的行为条件，更复杂的3D到达和舌头突起，发生在前皮层中。我们将首先证明在β衰减和单个单位调制时机中的传播序列发生在沿着主电动机的体形图的不同部分启动这些行为的每一个行为前皮层。其次，我们将在这些传播模式和运动之间提供因果关系通过应用亚阈值，电刺激的时空模式来启动。我们将证明当图案化刺激向自然传播序列传播时，运动开始会延迟但是当它模仿自然传播模式时，它不是。第三，我们将提供有关如何这些传播序列导致肌肉激活，该肌肉激活支持使用图案化的运动开始刺激触发的肌肉活动和肌肉解码。为了实现这些目标，四个高密度电极阵列将长期植入原发动机的上肢或口面区域，前皮层将同时记录100次单位和LFP。两个链接使用一组14个红外摄像机的外骨骼机器人和运动跟踪系统将监视手臂和手的运动学。应变量表将测量舌头和舌的运动学使用新型的3D X射线荧光镜系统跟踪。留置EMG电极还将测量手臂，手和舌头肌肉。将采用一组古典和新颖的计算方法表征运动开始过程中运动皮质活性的时空动力学。