CORTICOSPINAL CONTROL OF FORELIMB MOVEMENT

描述(改编自申请人的摘要)： 这是一项要求五年支持与 额叶皮质区的突触和功能组织 灵长类动物前肢运动的控制。最近几年，我们关于 额叶运动区和皮质脊髓输出组织发生了变化 戏剧性的。关于单神经元突触连接的信息 皮质脊髓细胞清楚地表明，这些细胞通常不会影响 只有一块肌肉，但组合肌肉作为功能性肌肉协同作用。 此外，存在着相当数量的离散运动前区域 灵长类动物的额叶已经变得清晰起来，每个额叶都有自己的补充 皮质脊髓神经元。在本应用程序中，我们建议在我们的 先前关于皮质运动区对大脑皮质运动区的贡献的研究 灵长类动物的前肢运动。这项建议集中在两个主要问题上。这个 首先基于我们最近的发现，很大一部分(45%) 参与伸展和抓取任务的皮质背核(CM)细胞 同时促进或抑制近端和近端的组合 棘波的远端肌肉触发了肌电活动的平均值(McKiernan et Al.，1998)。CM细胞靶肌肉的这些组合代表多个关节， 观察到的基本共激活模式下的功能肌肉协同效应 近端和远端肌肉在伸展和抓握运动中的作用 前肢。剩下的一个核心问题涉及到 细胞的远端和近端的靶肌肉。这样的细胞只会是 激活用于远端和近端肌肉被共同激活为 协同效应？我们希望解决的第二个问题涉及越来越多的证据 从大多数解剖学研究支持多个、离散的存在 额叶皮质内肢体肌肉的皮质脊髓表达 灵长类动物。除了建议的远端肌肉的双重表示外， 初级运动皮质，至少有六个运动前区被认为是基于 关于皮质脊髓神经元的解剖学标记和其他解剖学研究。 这些区域包括外侧半球的两个运动前区、SMA区和三个区 埋在扣带回里。尽管存在着大量的 皮质脊髓投射引发了人们的猜测，即这些区域代表着 用于直接接触运动神经元和运动控制的并行通道，在那里 很少有生理学研究对其疗效和特点进行研究 这些皮质脊髓投射与初级运动投射的比较 大脑皮层。这项提案的目标将是应用扣球和 刺激触发肌电活动的平均值，以映射和评估功能 这些多个皮质脊髓前肢表现的性质。

DESCRIPTION (Adapted From The Applicant's Abstract): This is a proposal requesting five years of support for work concerned with the synaptic and functional organization of frontal lobe cortical areas in the control of forelimb movements in primates. In recent years, our concepts about frontal lobe motor areas and corticospinal output organization have changed dramatically. Information about the synaptic connections of single corticospinal cells has shown clearly that these cells typically influence not just one muscle but combinations of muscles as functional muscle synergies. Moreover, the existence of a remarkable number of discrete premotor areas in the frontal lobe of primates has become clear, each with its own complement of corticospinal neurons. In this application we propose to build upon our previous studies concerning the contribution of the cortical motor areas to forelimb movement in primates. This proposal focuses on two major issues. The first builds upon our recent finding that a large fraction (45%) of corticomotoneuronal (CM) cells engaged in a reach and prehension task simultaneously facilitated or suppressed a combination of both proximal and distal muscles in spike triggered averages of EMG activity (McKiernan et al.,1998). These combinations of CM cell target muscles represent multi-joint, functional muscle synergies underlying basic coactivation patterns observed in proximal and distal muscle during reach and prehension movements of the forelimb. A central remaining question concerns the functional importance of the cell's distal and proximal target muscles. Will such cells only be activated for tasks in which the distal and proximal muscles are coactivated as a synergy? The second issue we wish to address concerns the mounting evidence from mostly anatomical studies favoring the existence of multiple, discrete corticospinal representations of limb muscles within the frontal cortex of primates. In addition to a proposed double representation of distal muscles in primary motor cortex, no less than six premotor areas have been suggested based on anatomical labeling of corticospinal neurons and other anatomical studies. These include two premotor areas in the lateral hemisphere, SMA and three areas buried in the cingulate gyrus. Although the presence of substantial corticospinal projections has prompted speculation that these areas represent parallel channels for direct access to motoneurons and movement control, there have been few physiological studies of the efficacy and characteristics of these corticospinal projections in comparison to those from primary motor cortex. The goal of this proposal will be to apply the techniques of spike and stimulus triggered averaging of EMG activity to map and assess the functional nature of these multiple corticospinal forelimb representations.