Porter R
Faculty of Medicine, Monash University, Clayton, Melbourne, Victoria, Australia.
Electroencephalogr Clin Neurophysiol. 1990 Oct;76(4):282-93. doi: 10.1016/0013-4694(90)90029-j.
At a time when both electrical and magnetic stimulation of the human brain are being used to assess cortical motor outflow in man, it is important to re-examine the organization of the motor areas of the cerebral cortex, the evidence which exists about the structures that are activated by epicortical stimulation, the nature of the projections from the cerebral cortex to lower motor centers, the physiological influences that are exerted on motoneurons and interneurons by these descending pathways and the relevance of all of these for the control of voluntary movement. This review examines the relationships of neuronal activities in some motor regions of the cerebral cortex to movement performance as revealed by recording of neuronal discharges during self-paced movements performed by conscious monkeys, and the relevance of these observations to the understanding of mechanisms of voluntary control of skilled movement performance in man. It documents detailed information about the precise connections made by descending cortico-motoneuronal fibers in the monkey and proposes a relationship between the analogous structural arrangements in man and the voluntary control of skilled movement. Comparison of some of the general propositions which derive from studies of cortico-motoneuronal commands in the monkey with the EMG results from magnetic stimulation in man leads to the suggestion that direct monosynaptic excitatory effects may be relevant to the control of both proximal and distal muscles in man. Electrical recordings of the neuronal activities of individual cells in strategic cytoarchitectonic areas of the monkey's cerebral cortex also provide a neurophysiological correlate of observations on regional cerebral blood flow and regional metabolism as these are studied in human subjects performing movement tasks. Hence it is possible to explain the involvement of supplementary motor areas of both hemispheres in the organization of the time-ordered commands for manual tasks. A deficit in bimanual coordination is evident in monkeys with a unilateral lesion of the supplementary motor area and this deficit mimics the disorder of voluntary control of bimanual manipulation reported in man.
在人脑的电刺激和磁刺激都被用于评估人类皮质运动输出的当下，重新审视大脑皮质运动区的组织、关于皮质表面刺激所激活结构的现有证据、从大脑皮质到下运动中枢的投射性质、这些下行通路对运动神经元和中间神经元施加的生理影响以及所有这些对于随意运动控制的相关性，是很重要的。本综述考察了在有意识的猴子进行自定步速运动期间通过记录神经元放电所揭示的大脑皮质某些运动区的神经元活动与运动表现之间的关系，以及这些观察结果对于理解人类熟练运动表现的随意控制机制的相关性。它记录了有关猴子中皮质 - 运动神经元下行纤维所形成的精确连接的详细信息，并提出了人类中类似结构安排与熟练运动的随意控制之间的关系。将从对猴子皮质 - 运动神经元指令的研究中得出的一些一般命题与人类磁刺激的肌电图结果进行比较，得出这样的建议：直接单突触兴奋效应可能与人类近端和远端肌肉的控制有关。对猴子大脑皮质关键细胞构筑区域中单个细胞的神经元活动进行电记录，也为在进行运动任务的人类受试者中所研究的局部脑血流和局部代谢的观察结果提供了神经生理学关联。因此，有可能解释双侧半球的辅助运动区在手部任务的时间顺序指令组织中的参与情况。在辅助运动区单侧损伤的猴子中，双手协调存在缺陷，这种缺陷类似于人类中所报道的双手操作随意控制障碍。
