Werhahn K J, Taylor J, Ridding M, Meyer B U, Rothwell J C
MRC Human Movement and Balance Unit, Institute of Neurology, the National Hospital for Neurology and Neurosurgery, London, UK.
Electroencephalogr Clin Neurophysiol. 1996 Feb;101(1):58-66. doi: 10.1016/0013-4694(95)00213-8.
There have been conflicting reports over whether it is possible to stimulate the human cerebellum through the intact scalp using transcranial magnetic stimulation. Here we attempt to clarify the situation in normal subjects by comparing the various methods which have been used. EMG responses evoked by magnetic stimulation over the motor cortex could be suppressed by a prior magnetic stimulus over the cerebellum but the onset latency of the effect varied according to the type of magnetic coil used. Inhibition began at a latency which ranged from 5 to 9 msec in different subjects if conditioning stimuli were given through a flat figure-of-eight coil held horizontally over the basal occiput. The effect lasted a further 6-10 msec. With a larger double cone coil, held vertically over the basal occiput, inhibition began earlier and at a more constant latency of 5 msec. It lasted only 3 msec. Stimulation of the C6/7 nerve roots in the brachial plexus with either an electrical or magnetic stimulus also could suppress EMG responses evoked by cortical stimulation. This began at a conditioning-test interval of 7 or 8 msec and lasted for some 5 msec. We suggest that two types of motor cortical suppression may be elicited from stimulation over the posterior neck/skull: a cerebellar effect starting at 5 msec, and a peripheral nerve effect starting later at 7/8 msec. Stimulation with a horizontal large figure-of-eight coil may produce a mixture of effects because the lower wing of the coil overlaps the posterior neck and can activate peripheral nerve fibres in the brachial plexus.
关于是否能够通过完整头皮使用经颅磁刺激来刺激人类小脑，一直存在相互矛盾的报道。在此，我们试图通过比较已使用的各种方法来澄清正常受试者的情况。运动皮层磁刺激诱发的肌电图反应可被先前小脑磁刺激所抑制，但效应的起始潜伏期根据所使用的磁线圈类型而有所不同。如果通过水平放置在枕骨基部上方的扁平8字形线圈给予条件刺激，抑制在不同受试者中起始潜伏期为5至9毫秒。效应持续另外6 - 10毫秒。使用更大的双锥线圈，垂直放置在枕骨基部上方，抑制更早开始，且更恒定的潜伏期为5毫秒。它仅持续3毫秒。用电刺激或磁刺激刺激臂丛神经中的C6/7神经根也可抑制皮层刺激诱发的肌电图反应。这在条件刺激 - 测试间隔为7或8毫秒时开始，持续约5毫秒。我们认为，在后颈部/颅骨上方进行刺激可能引发两种类型的运动皮层抑制：一种是在5毫秒开始的小脑效应，另一种是在7/8毫秒稍后开始的外周神经效应。使用水平大8字形线圈进行刺激可能会产生混合效应，因为线圈的下翼与后颈部重叠，可激活臂丛神经中的外周神经纤维。
