Coding of Action by Motor & Premotor Cortical Ensembles

电机动作编码

基本信息

批准号：
10377916
负责人：
Nicholas G Hatsopoulos
金额：
$ 46.77万
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 2024-03-31
项目状态：
已结题

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.

抽象的该项目的目标是了解运动皮层活动的时空模式是如何启动的不同类型的随意运动。运动皮质神经元的大型分布式集合开始在自愿运动之前调节它们的发射率，并被认为因果地产生这些动作。然而，仍然没有解决为什么在单次类似调制时没有启动运动的问题。单位运动皮层活动发生在运动计划、想象和视觉观察动作的过程中。这已知 Beta 频率 (15-40 Hz) 范围内的局部场电位 (LFP) 振荡幅度会衰减在运动开始之前，被认为是皮质脊髓兴奋性的介观特征。我们有最近在初级中发现了 LFP beta 衰减和单单元调制时序的顺序模式运动皮层在运动开始之前（但在运动过程中）没有进行空间组织准备。我们的工作假设是，这种传播顺序模式对于启动移动。在这个项目中，我们将通过证明这种传播来测试和扩展这个假设模式概括为不同行为的运动启动，包括不同行为下的 2D 到达条件下，更复杂的 3D 抓握和舌头突出发生在运动前皮层。我们首先会证明β衰减和单单元调制定时中的传播序列发生在这些行为中的每一种都沿着初级运动体位图的不同部分启动，前运动皮质。其次，我们将提供这些传播模式和运动之间的因果关系通过应用阈下、时空模式的电刺激来启动。我们将证明当模式化刺激与自然传播顺序相反时，运动启动就会延迟但当它模仿自然传播模式时就不是这样了。第三，我们将提供一个机制解释这些传播序列导致肌肉激活，从而支持使用图案化的运动启动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初级运动和控制的上肢或口面部区域运动前皮层将同时记录数百个单个单元和 LFP。一个二连杆外骨骼机器人和使用一组十四个红外摄像机的运动跟踪系统将监控手臂和手的运动学。应变计将测量舌头的力，并且舌头的运动学将被使用新型 3D X 射线透视系统进行跟踪。留置肌电图电极也将测量来自手臂、手和舌头的肌肉。将采用一套经典和新颖的计算方法表征运动启动过程中运动皮层活动的时空动态。