CORTICOSPINAL CONTROL OF FORELIMB MOVEMENT

描述（改编自申请人的摘要）： 这是一项要求在五年内支持与下列方面有关的工作的提案： 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。近年来，我们对 额叶运动区和皮质脊髓输出组织已经改变 戏剧性地。关于单个突触连接的信息 皮质脊髓细胞清楚地表明，这些细胞通常不影响 只有一块肌肉，但肌肉的组合作为功能肌肉协同作用。 此外，存在一个显着数量的离散运动前区， 灵长类动物的额叶已经变得清晰，每一个都有自己的补充， 皮质脊髓神经元在本申请中，我们建议建立在我们的 以前的研究关于皮质运动区的贡献， 灵长类动物的前肢运动。这项建议集中在两个主要问题上。的 首先建立在我们最近的发现，一大部分（45%）的 皮质运动神经元（CM）细胞参与伸展和伸展任务 同时促进或抑制了近端和远端的结合， 在尖峰触发的EMG活动的平均值中的远端肌肉（McKiernan et 例如，1998年）。CM细胞靶肌肉的这些组合代表多关节， 功能性肌肉协同作用的基础上观察到的基本共激活模式， 近端和远端肌肉在达到和伸展运动的过程中， 前肢一个悬而未决的核心问题是， 细胞的远端和近端目标肌肉。这种细胞只会 激活用于远端和近端肌肉共同激活的任务， 协同效应我们要谈的第二个问题是， 大多数解剖学研究支持存在多个离散的 额叶皮层内肢体肌肉的皮质脊髓代表 灵长类动物除了建议的远端肌肉的双重表示外， 初级运动皮层，不少于六个运动前区已建议基于 皮质脊髓神经元的解剖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和三个区域 埋在扣带回里虽然存在大量的 皮质脊髓投射促使人们推测这些区域代表了 平行通道直接进入运动神经元和运动控制，有 很少有生理学研究的功效和特点， 这些皮质脊髓投射与来自初级运动神经的投射相比， 皮层本提案的目标是应用扣球技术， 刺激触发EMG活动的平均，以映射和评估功能 这些多皮质脊髓前肢代表的性质。

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.