Coding of action by motor & premotor cortical ensembles

描述（由申请人提供）：本项目的目标是了解单个神经元以及多个运动皮层区域中相互作用的神经元的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，手的运输和把握预成形的协调，很少有人知道皮质参与协调达到和把握。大多数电生理记录都集中在表征单个皮层神经元的放电，这些神经元分别与伸手或抓握运动有关。我们将确定：1）背侧前运动区（PMd）、腹侧前运动区（PMv; F5）和初级运动区（MI）的单个神经元是如何通过明确表征伸手抓握协调的编码来编码伸手和抓握成分的; 2）这三个皮层区域内是否存在伸手和抓握神经元的拓扑组织;以及3）在同时记录的神经元之间是否存在结构化的时空尖峰模式，其介导了伸手抓握的协调。为了实现这一点，将高密度电极阵列长期植入MI、PMv和PMd中，当猴子在不同的三维位置伸手抓住不同尺寸、形状和方向的物体时，将同时记录100个单个单元和局部场电位。使用一组六个红外摄像机的数字光学跟踪系统将在伸手抓握行为期间监测手臂和手的运动学。一组统计和数学方法将被用来开发编码模型的达到把握，捕捉如何单神经元尖峰和神经元合奏活动参与协调的手运输和握孔运动学。解码模型也将用于比较MI，PMv和PMd内的集成活动如何重建到达和抓取运动学。涉及避障和抓取移动物体的更复杂的伸手抓握运动将被用来测试这些编码和解码模型是否适用于改变的协调模式。公共卫生相关性：协调的接触和抓取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觅食，并允许发展更复杂的行动，包括工具的使用，并最终通过直接接触获得知识。拟议的项目将提高我们对这些协调行为的皮质贡献的理解，这可能会导致更有效的康复治疗运动残疾患者因中风或受伤而导致的皮质损伤。这项工作也有直接相关的神经运动假体的发展，脊髓损伤或ALS患者可能能够控制把握以及运输组件的人工设备通过激活运动皮层神经元的合奏。

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.