Hashimoto R, Rothwell J C
MRC Human Movement and Balance Unit, Institute of Neurology, London, UK.
Exp Brain Res. 1999 Mar;125(1):75-81. doi: 10.1007/s002210050660.
We investigated temporal changes in the amplitudes of motor-evoked potentials (MEPs) induced by transcranial magnetic stimulation over the left motor cortex during motor imagery. Nine subjects were instructed to imagine repetitive wrist flexion and extension movements at 1 Hz, in which the flexion timing was cued by a tone signal. Electromyographs (EMGs) were recorded from the first dorsal interosseous, flexor carpi radialis and extensor carpi radialis muscles of the right hand, and magnetic stimulation was delivered at 0, 250, 500 and 750 ms after the auditory cue. On average, the evoked EMG responses were larger in the flexor muscle during the phase of imagined flexion than during extension, whilst the opposite was true for the extensor muscle. There were no consistent changes in the amplitudes of MEPs in the intrinsic hand muscle (first dorsal interosseous). The EMG remained relaxed in all muscles and did not show any significant temporal changes during the test. The H-reflex in the flexor muscle was obtained in four subjects. There was no change in its amplitude during motor imagery. These observations lead us to suggest that motor imagery can have dynamic effects on the excitability of motor cortex similar to those seen during actual motor performance.
我们研究了在运动想象过程中，经颅磁刺激左侧运动皮层所诱发的运动诱发电位（MEP）幅度的时间变化。九名受试者被要求以1赫兹的频率想象重复性的手腕屈伸运动，其中屈腕时间由音调信号提示。从右手的第一背侧骨间肌、桡侧腕屈肌和桡侧腕伸肌记录肌电图（EMG），并在听觉提示后0、250、500和750毫秒给予磁刺激。平均而言，在想象屈腕阶段，屈肌诱发的EMG反应比伸腕阶段更大，而伸肌则相反。手部固有肌（第一背侧骨间肌）的MEP幅度没有一致的变化。在测试过程中，所有肌肉的EMG均保持松弛，未显示出任何明显的时间变化。在四名受试者中获得了屈肌的H反射。在运动想象过程中其幅度没有变化。这些观察结果使我们认为，运动想象对运动皮层兴奋性可产生与实际运动表现中类似的动态影响。
