TRANSCRANIAL MAGNETIC STIMULATION OVER THE POSTERIOR CEREBELLUM DURING VISUALLY GUIDED SACCADES IN MAN
TRANSCRANIAL MAGNETIC STIMULATION OVER THE POSTERIOR CEREBELLUM DURING VISUALLY GUIDED SACCADES IN MAN
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DOI：
10.1093/brain/118.5.1185
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发表时间：
1995-10-01
期刊：
影响因子：
14.5
通讯作者：
OHTSUKA, K
中科院分区：
文献类型：
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作者：
HASHIMOTO, M;OHTSUKA, K
最近在猴子身上进行的密集的神经生理学实验证明了小脑在控制眼跳运动中的功能。对猴子的微刺激研究已经确定，专门参与眼跳控制的小脑皮质位于Vermal小叶Vic和Vi。从这个Vermal区发出的浦肯野细胞轴突几乎完全终止于一个椭圆形区域，该区域从顶核的背尾部突出。顶核中的眼跳相关细胞仅位于椭圆形区域。微电刺激蚯蚓调节顶核中与眼跳相关的细胞的活动，然后产生眼球跳动。在这项研究中，我们使用经颅磁刺激(TMS)设备研究了小脑刺激对男性眼跳指标的影响。在6名正常受试者的水平视觉引导眼跳中，在小脑后部类似于小脑外侧和尾侧7 mm的区域进行了焦点TMS检查。TMS设备在眼跳开始后触发，潜伏期为0、20、40或60毫秒。我们研究了TMS对眼球跳动幅度和速度的影响。对于与刺激正弦相反侧的视觉引导眼跳，潜伏期为0ms的小脑后部TMS产生低速眼跳，然后是矫正眼跳。潜伏期分别为20、40和60ms的经颅磁刺激对眼跳指标无影响。另一方面，对于同侧眼跳，潜伏期为0、20和40ms的TMS会产生超长的眼跳，然后出现后眼跳漂移。潜伏期为60ms的经颅磁刺激对眼跳指标无影响。TMS患者的同侧眼跳峰值速度明显高于相同波幅的正常眼跳。这些发现与之前对猴子的神经生理学观察一致。
Recent intensive neurophysiological experiments in the monkey have demonstrated the function of the cerebellum in the control of saccadic eye movements. Microstimulation studies on monkeys have determined that the cerebellar cortex, which is specifically involved in the control of saccades, is located in vermal lobules VIc and VII. The Purkinje-cell axons arising from this vermal area terminate almost exclusively in an ellipsoidal region which protrudes dorsocaudally from the fastigial nucleus. Saccade-related cells in the fastigial nucleus are located exclusively in the ellipsoidal region. Microstimulation of the vermis modulated the activity of saccade-related cells in the fastigial nucleus, and then produced dysmetric saccades. In this study, we investigated effects of cerebellar stimulation on saccade metrics in man using a transcranial magnetic stimulation (TMS) device. Focal TMS was applied over the posterior cerebellum at an area similar to 7 mm lateral and caudal to the inion during horizontal visually guided saccades in six normal subjects. The TMS device was triggered after the onset of saccades with a latency of 0, 20, 40 or 60 ms. We investigated the effect of TMS on the amplitude and velocity of saccadic eye movements. For visually guided saccades directed contralateral to the stimulation sine, TMS of the posterior cerebellum with the latency of 0 ms produced hypometric saccades followed by corrective saccades. Transcranial magnetic stimulation with latencies of 20, 40 and 60 ms had no effect on saccade metrics. On the other hand for ipsilateral saccades, TMS with latencies of 0, 20 and 40 ms produced hypermetric saccades followed by postsaccadic drift. Transcranial magnetic stimulation with the latency of 60 ms had no effect on saccade metrics. The peak velocity of ipsilateral saccades with TMS was significantly gl-eater than that of normal saccades with the same amplitude. These findings are consistent with previous neurophysiological observations in the monkey.