Donoghue J P, Sanes J N
Department of Neuroscience, Brown University, Providence, Rhode Island 02912.
J Clin Neurophysiol. 1994 Jul;11(4):382-96.
The motor cortex includes several areas in the frontal agranular cortex. These areas receive inputs from sensory pathways, motor control structures, other cortical areas, and from "modulatory" pathways. Motor cortical outputs are widely distributed to many other parts of the nervous system and can thereby influence each of the major descending motor control pathways and spinal motor circuitry. The most intensively studied motor areas, the premotor area (PMA), supplementary motor area (SMA), and primary motor cortex (MI), appear to have different roles in movement. PMA is involved in coupling arbitrary cues to motor acts, whereas SMA appears to participate more in internal guidance or planning of movement. While MI has been implicated in control of muscle force or length, more recent data suggest that it encodes higher order parameters, such as movement direction. Two new views of motor cortex are presented. First, it is argued that MI contains functional subdivisions of the face, arm, and leg, and that each subdivision contains a highly overlapping, extensively interconnected and non-topographic internal organization. Second, motor representations can reorganize rapidly as a consequence of experience or peripheral lesions. These changes may arise through modifications in synaptic coupling among motor cortex neurons. These features of motor cortex suggest a role for motor cortex in learning and in performing voluntary movements.
运动皮层包括额叶无颗粒皮层中的几个区域。这些区域接收来自感觉通路、运动控制结构、其他皮层区域以及“调制”通路的输入。运动皮层输出广泛分布于神经系统的许多其他部位，从而能够影响每条主要的下行运动控制通路和脊髓运动回路。研究最为深入的运动区域，即运动前区（PMA）、辅助运动区（SMA）和初级运动皮层（MI），在运动中似乎具有不同的作用。PMA参与将任意线索与运动行为相耦合，而SMA似乎更多地参与运动的内部引导或规划。虽然MI一直被认为与肌肉力量或长度的控制有关，但最近的数据表明它编码更高阶的参数，如运动方向。本文提出了关于运动皮层的两种新观点。首先，有人认为MI包含面部、手臂和腿部的功能分区，并且每个分区都包含高度重叠、广泛互连且非拓扑的内部组织。其次，运动表征可因经验或外周损伤而迅速重组。这些变化可能通过运动皮层神经元之间突触耦合的改变而产生。运动皮层的这些特征表明其在学习和执行自主运动中发挥作用。
