Sequential activation of neurons in primate motor cortex during unrestrained forelimb movement.
Sequential activation of neurons in primate motor cortex during unrestrained forelimb movement.
复制标题
在不受限制的前肢运动过程中灵长类运动皮层神经元的顺序激活。
作者：
J. Murphy;Y. Wong;H. Kwan
我们训练猴子做一种不受约束的伸展手臂的动作。前肢肌肉的肌电图（EMG）记录显示，参与任务的肌肉群从近端到远端依次激活。肌电图活动在近端（肩部和肘部）和远端（手腕和手指）肌肉之间的延迟大约为60毫秒。我们通过先前定义的标准，包括对体感觉刺激的反应和皮质内微刺激的影响，确定了对侧运动皮层前肢区域的神经元控制特定关节。许多细胞在作用于相应关节的肌电图活动开始之前放电，而其他细胞则在运动的较晚阶段开始放电。所有近端细胞群改变放电模式的时间大约比远端细胞群早60毫秒。一小部分细胞在放电频率上表现出最初的抑制性变化，这种抑制通常发生在大多数细胞的兴奋性变化之前。根据前肢运动皮层的“巢区”模型对结果进行了讨论。这些数据支持了该模型的一个预测，即皮质区域内已识别细胞的放电与前肢适当关节的随意运动有因果关系。
We trained monkeys to perform an unrestrained, reaching movement of the arm. Electromyogram (EMG) recordings of forelimb muscles revealed sequential activation, proximal to distal, of muscle groups involved in the task. The delay in onset of EMG activity between proximal (shoulder and elbow) and distal (wrist and finger) muscles was approximately 60 ms. We identified the neurons in the forelimb area of the contralateral motor cortex as controlling particular joints by previously defined criteria involving responses to somatosensory stimulation and effects of intracortical microstimulation. Many cells discharged prior to the onset of EMG activity acting on the appropriate joint, whereas others began firing at a later phase of the movement. The population of all proximal cells altered discharge patterns approximately 60 ms earlier than the population of distal cells. A small percentage of cells showed an initial inhibitory change in discharge frequency, and this inhibition typically occurred prior to the excitatory changes seen in the majority of cells. The results are discussed in terms of the "nested-zone" model of the forelimb motor cortex. The data support one of the predictions of this model, namely that discharges of identified cells within the cortical zones are causally related to voluntary movement at appropriate forelimb joints.