Central Control of Movement

我们的长期目标是确定负责中枢生成的神经基质， 控制自主运动。在本提案中，我们将探讨这种基板的一个主要组成部分- 初级运动皮层（M1）。在最近的解剖学实验中，我们发现M1不是一个 它是一个统一的区域，但有两个细分。M1的“新”分支只存在于一些猴子中， 类人猿和人类。它包含输出神经元，轴突下降到脊髓， 与运动神经元的直接联系这些神经元被称为皮质运动神经元（CM）细胞。在 相比之下，M1的“旧”亚类是大多数哺乳动物物种的标准。旧M1包含输出 神经元下降到脊髓，但只通过与运动神经元的相互作用间接影响运动神经元。 脊髓中间神经元M1包含两个细分的证明提出了一个重要的问题-- 在新旧M1中表现和控制的运动方面有什么不同？ 存在用于鉴定CM细胞的生理学方法。此外，我们有一个独特的行为， 范式，使我们能够定义在皮层神经元活动中编码的运动方面， 手腕动作。我们的范例，沿着CM细胞的生理鉴定，将使我们能够回答 一个关键的问题-CM细胞发送给运动神经元的下行命令的性质是什么？ 为了解决这些问题，我们将在我们的范式上训练猴子， 与运动生成相关的帧-肌肉活动，关节运动（内在参数）和 作用方向（外部参数）。然后，我们将记录M1中单个神经元的活动， 任务我们将对位于中央前回表面皮质中并被埋藏的旧M1和新M1进行采样 在中央前沟的前部此外，我们将长期记录10-12的活动 植入前臂的肌肉我们将使用肌肉活动的尖峰触发平均来识别CM 细胞分析的结果将使我们能够确定：i）发出的运动指令的性质 由M1神经元对运动行为有直接影响，以及ii）所代表的运动方面， 在旧的和新的M1控制。总的来说，我们提出的实验结果将提供新的 关于M1的功能、其细分及其在规划、生成和控制中的作用的信息 运动

Our long-term goal is to define the neural substrate that is responsible for the central generation and control of voluntary movement. In this proposal we will explore one major component of this substrate- the primary motor cortex (M1). In the course of recent anatomical experiments, we discovered that M1 is not a uniform area, but rather has two subdivisions. The "New" subdivision of M1 is only present in some monkeys, great apes and humans. It contains output neurons with axons that descend to the spinal cord and make direct connections with motoneurons. These neurons are termed cortico-motoneuronal (CM) cells. In contrast, the "Old" subdivision of M1 is the standard for most mammalian species. Old M1 contains output neurons that descend to the spinal cord, but influence motoneurons only indirectly through interactions with spinal interneurons. The demonstration that M1 contains two subdivisions raises an important question- Do the aspects of movement represented and controlled in Old and New M1 differ? Physiological methods exist for identifying CM cells. In addition, we have a unique behavioral paradigm which enables us to define the aspect of movement encoded in the activity of cortical neurons during wrist movement. Our paradigm, along with the physiological identification of CM cells, will allow us to answer a critical question- What is the nature of the descending commands that CM cells send to motoneurons? To address these questions, we will train monkeys on our paradigm which dissociates 3 reference frames associated with movement generation- muscle activity, joint movement (intrinsic parameters) and direction of action (an extrinsic parameter). Then, we will record the activity of single neurons in M1 during the task. We will sample Old M1 and New M1 which lie in cortex on the surface of the precentral gyrus and buried in the anterior bank of the precentral sulcus. In addition, we will record the activity of 10-12 chronically implanted muscles in the forearm. We will use spike-triggered averaging of the muscle activity to identify CM cells. The results from this analysis will enable us to determine: i) the nature of the motor commands issued by M1 neurons with a direct influence on motor behavior and ii) the aspects of movement represented and controlled in Old and New M1. Overall, the results from our proposed experiments will provide novel information about the functions of M1, its subdivisions and its role in the planning, generation and control of movement.