Rothwell J C, Higuchi K, Obeso J A
MRC Human Movement and Balance Unit, Institute of Neurology, Queen Square, London, UK.
Mov Disord. 1998 Mar;13(2):330-5. doi: 10.1002/mds.870130221.
Nine normal subjects were asked to make either a brisk isometric pinch of a force transducer held between the forefinger and thumb, or to hold a pinch for approximately 15 s and then release the force suddenly without any overt antagonist contraction. EEG activity was averaged about the onset or offset of EMG activity, and movements were made in the subjects' own time. All subjects found the task simple. The EEG activity preceding offset of contraction (offset cortical potential) was significantly smaller in lateral leads than that seen before onset of contraction. Midline activation was similar in both tasks. We suggest that in the onset task, motor cortex activity related to the act to be performed contributes substantially to the EEG potentials in lateral leads. This activity is absent in the offset task which requires only withdrawal of tonic input to motor cortex. Midline activity, common to both onset and offset tasks, could reflect timing, attentional, or other processes. The results are discussed in relation to previous data from an isotonic relaxation task.
九名正常受试者被要求用食指和拇指快速等长挤压一个力传感器，或者保持挤压约15秒，然后突然松开，且没有任何明显的拮抗肌收缩。脑电图活动在肌电图活动开始或结束时进行平均，动作由受试者自行决定时间完成。所有受试者都认为这项任务很简单。收缩结束前的脑电图活动（结束皮层电位）在外侧导联明显小于收缩开始前的活动。中线激活在两项任务中相似。我们认为，在开始任务中，与要执行的动作相关的运动皮层活动在很大程度上促成了外侧导联的脑电图电位。在结束任务中不存在这种活动，该任务仅需要撤回对运动皮层的紧张性输入。开始和结束任务共有的中线活动可能反映了时间、注意力或其他过程。结合等张放松任务的先前数据对结果进行了讨论。
