Di Lazzaro V, Oliviero A, Pilato F, Saturno E, Insola A, Mazzone P, Tonali P A, Rothwell J C
Institute of Neurology, Università Cattolica, L.go A. Gemelli 8, 00168 Rome, Italy.
Clin Neurophysiol. 2002 Jan;113(1):114-9. doi: 10.1016/s1388-2457(01)00696-4.
To directly compare the volleys evoked by figure-of-eight and circular magnetic coil stimulation of the motor cortex and to correlate the descending volleys with the EMG responses in distal hand muscles.
Descending corticospinal volleys were recorded from an electrode inserted into the cervical epidural space of two conscious human subjects after transcranial stimulation of the hand area of the motor cortex. We compared volleys evoked by stimulation with (a) a figure-of-eight coil inducing posterior-anterior or latero-medial currents in the brain, (b) a large circular coil centred at the vertex inducing clockwise currents in the brain, and (c) anodal electric pulses.
For a given amplitude of EMG response in the first dorsal interosseous muscle, volleys were larger after stimulation with a circular than a figure-of-eight coil. In addition, the D wave evoked by circular coil stimulation had a longer latency than the anodal D wave, and increased in amplitude when stimulation was given during voluntary contraction.
We conclude that stimulation with a large circular coil activates descending outputs less selectively than figure-of-eight coil stimulation and that it is capable of activating pyramidal neurones at the initial segment region.
直接比较“8”字形和圆形磁线圈刺激运动皮层所诱发的波群，并将下行波群与手部远端肌肉的肌电图反应相关联。
在对两名清醒人类受试者的运动皮层手部区域进行经颅刺激后，从插入颈段硬膜外间隙的电极记录下行皮质脊髓束波群。我们比较了以下刺激所诱发的波群：(a) 一个“8”字形线圈，在脑内诱发后 - 前或外侧 - 内侧电流；(b) 一个以头顶为中心的大圆形线圈，在脑内诱发顺时针电流；(c) 阳极电脉冲。
对于第一背侧骨间肌中给定幅度的肌电图反应，圆形线圈刺激后的波群比“8”字形线圈刺激后的波群更大。此外，圆形线圈刺激诱发的D波潜伏期比阳极D波长，并且在自主收缩期间给予刺激时，其幅度会增加。
我们得出结论，大圆形线圈刺激比“8”字形线圈刺激激活下行输出的选择性更低，并且它能够在起始节段区域激活锥体神经元。
