Coding of action by motor & premotor cortical ensembles

描述（由申请人提供）：该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群如何在伸手抓握行为中协调近端和远端成分。虽然心理物理学研究已经确定，可握握性运动涉及手移动和抓握预成型的协调，但对协调伸手和抓握的皮质参与知之甚少。大多数电生理记录都集中在单个皮层神经元的放电特征上，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（PMd）、腹侧前运动（PMv; F5）和初级运动（MI）皮质区域内的单个神经元如何通过明确表征手-抓协调的编码来编码伸手和抓握成分；2)在这三个皮层区域内是否存在到达和抓取神经元的地形组织；3)在同时记录的神经元中，是否存在结构化的脉冲时空模式，以调节手抓协调。为了实现这一目标，高密度电极阵列将被长期植入MI、PMv和PMd，当猴子在不同的三维位置触摸和抓住不同大小、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。数字光学跟踪系统使用一组六台红外摄像机来监测手臂和手在伸手抓握过程中的运动学。将采用一组统计和数学方法来开发触手到抓取的编码模型，该模型捕获单个神经元峰值和神经元集合活动如何参与手部运输和抓取孔径运动学的协调。解码模型还将用于比较MI， PMv和PMd中的集成活动如何重建到达和掌握运动学。涉及避障和抓取移动物体的更复杂的伸手抓握动作将用于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：协调伸手和抓握是人类行为的普遍特征，其进化根源可追溯到灵长类动物在树木环境中觅食，并允许发展更复杂的行动，包括工具使用，并最终通过直接接触获取知识。该项目将增强我们对皮质对这些协调行为的贡献的理解，这可能会为中风或损伤引起的皮质损伤的运动残疾患者带来更有效的康复治疗。这项工作也与神经运动假体的发展直接相关，通过这种假体，脊髓损伤或ALS患者可以通过激活运动皮质神经元群来控制人工装置的抓取和运输成分。

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.