Coding of action by motor & premotor cortical ensembles

描述(申请人提供)：本项目的目标是了解单个神经元以及多个运动皮质区域中相互作用的神经元集合如何在伸手抓握行为中协调近端和远端组件。虽然心理物理学研究已经确定抓握运动涉及手部运输和抓握预塑的协调，但对大脑皮质参与协调伸展和抓握知之甚少。大多数电生理记录都集中在描述单个皮层神经元的放电与分别到达或抓取运动的关系。我们将确定：1)背侧前运动(PMD)、腹侧前运动(PMV；F5)和初级运动(MI)皮质区中的单个神经元如何通过明确表征REACH-to-GRANSE协调的编码来编码到达和抓取组件；2)在这三个皮质区内是否存在REACH和GRIPT神经元的拓扑组织；以及3)同时记录的神经元之间是否存在调节REACH-TO-GRAP协调的结构化时空模式。为了实现这一点，高密度电极阵列将被长期植入MI、PMV和PMD中，从那里将同时记录100s的单个单位和局部场电位，而猴子在不同的三维位置伸手和抓住不同大小、形状和方向的物体。使用一组六个红外摄像头的数字光学跟踪系统将监测手臂和手在伸手抓握行为中的运动学。一套统计和数学方法将被用来开发伸展到抓取的编码模型，该模型捕捉单个神经元尖峰和神经元集合活动如何参与手部运输和握力孔运动学的协调。解码模型也将被用来比较MI、PMV和PMD内的整体活动在多大程度上能够重建伸展和掌握运动学。更复杂的伸手抓握动作，包括躲避障碍物和抓住移动物体，将被用来测试这些编码和解码模型是否概括为改变的协调模式。与公共健康相关：协调的接触和掌握是人类行为的一个普遍特征，其进化根源可以追溯到灵长类动物在树栖环境中寻找食物，并允许发展更复杂的行动，包括使用工具，并最终通过直接接触获得知识。拟议的项目将加深我们对皮质对这些协调行为的贡献的理解，这可能会导致对因中风或损伤而导致皮质损伤的运动障碍患者进行更有效的康复治疗。这项工作还与神经运动假体的开发有直接关系，通过这种假体，脊髓受损或ALS患者可能能够通过激活运动皮质神经元集合来控制人工设备的抓取和运输组件。

DESCRIPTION (provided by applicant): The goal of this project is to understand how single neurons as well as ensembles of interacting neurons in multiple motor cortical areas coordinate proximal and distal components in reach-to-grasp behavior. Although psychophysical research has determined that prehensile movements involve the coordination of hand transport and grasp preshaping, very little is known about the cortical involvement in coordinating reach and grasp. Most electrophysiological recordings have focused on characterizing the firing of single cortical neurons in relation to either reaching or grasping movements separately. We will determine: 1) how single neurons within dorsal premotor (PMd), ventral premotor (PMv; F5), and primary motor (MI) cortical areas encode both reach and grasp components by explicitly characterizing the encoding of reach-to-grasp coordination; 2) whether there is a topographic organization of reach and grasp neurons within these three cortical areas; and 3) whether there are structured spatiotemporal patterns of spiking among simultaneously recorded neurons that mediate the coordination of reach-to-grasp. To accomplish this, high-density electrode arrays will be chronically implanted in MI, PMv, and PMd from which 100s of single units and local field potentials will be simultaneously recorded while monkeys reach for and grasp objects of different sizes, shapes, and orientations in different three-dimensional locations. A digital optical tracking system using a set of six infrared cameras will monitor the kinematics of the arm and hand during reach-to-grasp behavior. A set of statistical and mathematical methods will be employed to develop encoding models of reach-to-grasp that capture how single neuron spiking and neuronal ensemble activity participate in the coordination of hand transport and grip aperture kinematics. Decoding models will also be used to compare how well ensemble activity within MI, PMv, and PMd can reconstruct the reach and grasp kinematics. More complex reach-to-grasp movements involving obstacle avoidance and grasp of moving objects will be used to test whether these encoding and decoding models generalize to altered coordination patterns. PUBLIC HEALTH RELEVANCE: Coordinated reaching and grasping is a ubiquitous feature of human behavior that traces its evolutionary roots to primate foraging for food in arboreal environments and has allowed for the development of more complex actions including tool use and, ultimately, knowledge acquisition through direct contact. The proposed project will enhance our understanding of the cortical contribution to these coordinated behaviors which may lead to more effective rehabilitative treatments for motor disabled patients with cortical damage due to stroke or injury. This work also has direct relevance towards the development of a neuro-motor prosthesis by which spinal cord-damaged or ALS patients may be able to control grasp as well as transport components of artificial devices by activating ensembles of motor cortical neurons.