INTERHEMISPHERIC INHIBITION OF THE HUMAN MOTOR CORTEX
INTERHEMISPHERIC INHIBITION OF THE HUMAN MOTOR CORTEX
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DOI：
10.1113/jphysiol.1992.sp019243
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发表时间：
1992-07-01
影响因子：
5.5
通讯作者：
MARSDEN, CD
中科院分区：
文献类型：
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作者：
FERBERT, A;PRIORI, A;MARSDEN, CD
1.使用两个磁刺激器。我们研究了在一侧大脑半球的运动皮层上施加条件性磁刺激对在另一侧大脑半球施加磁测试刺激在第一背侧骨间肌（FDI）中诱发的肌电反应大小的影响.当条件反射-测试间隔为5-6 ms或更长时，对一侧半球的单次条件反射电击产生对另一侧半球诱发的测试反应的抑制。我们称之为半球间抑制。然而，使用表面EMG反应观察到的抑制的最小潜伏期可能低估了真正的半球间传导时间。单运动单位研究表明，该值比表面EMG观察到的最小间隔长4-7 ms。当测试肌肉活动或放松时，观察到半球间抑制。增加条件刺激强度，抑制持续时间增加;增加测试刺激强度，抑制深度减少.调节线圈必须放置在头皮的适当区域，以产生抑制。当条件刺激作用于运动皮层的手部区域时，其作用最大，当刺激向该点内侧或外侧移动时，其作用减弱.对测试刺激的抑制作用可能发生在大脑皮层水平。相反，磁测试刺激引起的测试反应的抑制，测试反应引起的积极FDI由一个小的阳极电击对侧磁条件刺激没有显着抑制。同样，H反射放松前臂屈肌不受条件刺激同侧半球。然而，如果在肌肉活动的情况下重复实验，则观察到抑制。当测试肌肉放松时，条件半球对侧的手的肌肉的随意收缩可以稍微增加半球间抑制的量。如果测试肌肉在整个实验中保持活跃，这种效果就会消失。在一个半球的磁条件刺激也能够影响正在进行的自愿EMG活动在同侧FDI。抑制开始后10-15 ms的最小皮质脊髓传导时间到肌肉，并持续约30 ms。抑制的深度近似成正比的水平正在进行的肌电图。在前臂屈肌中也观察到类似的抑制期，但在二头肌中不太清楚，有时在兴奋之前。这些实验中描述的半球间抑制可能是通过胼胝体途径产生的。
1. Using two magnetic stimulators. we investigated the effect of a conditioning magnetic stimulus over the motor cortex of one hemisphere on the size of EMG responses evoked in the first dorsal interosseous (FDI) muscle by a magnetic test stimulus given over the opposite hemisphere.2. A single conditioning shock to one hemisphere produced inhibition of the test response evoked from the opposite hemisphere when the conditioning-test interval was 5-6 ms or longer. We shall refer to this as interhemispheric inhibition. However, the minimum latency of inhibition observed using surface EMG responses may have underestimated the true interhemispheric conduction time. Single motor unit studies suggested values 4-7 ms longer than the minimum interval observed with surface EMG.3. lnterhemispheric inhibition was seen when the test muscle was active or relaxed. Increasing the intensity of the conditioning stimulus increased the duration of inhibition: increasing the intensity of the test stimulus reduced the depth of inhibition.4. The conditioning coil had to be placed on the appropriate area of scalp for inhibition to occur. The effect of the conditioning stimulus was maximal when it was applied over the hand area of motor cortex, and decreased when the stimulus was moved medial or lateral to that point.5. The inhibitory effect on the test stimulus probably occurred at the level of the cerebral cortex. In contrast to the inhibition of test responses evoked by magnetic test stimuli, test responses evoked in active FDI by a small anodal electric shock were not significantly inhibited by a contralateral magnetic conditioning stimulus. Similarly, H reflexes in relaxed forearm flexor muscles were unaffected by conditioning stimuli to the ipsilateral hemisphere. However, inhibition was observed if the experiment was repeated with the muscles active.6. When the test muscle was relaxed, the amount of interhemispheric inhibition could be increased slightly by voluntary contraction of the muscles in the hand contralateral to the conditioning hemisphere. This effect disappeared if the test muscle was held active throughout the experiment.7. Magnetic conditioning stimuli over one hemisphere were also capable of affecting on-going voluntary EMG activity in the ipsilateral FDI. Inhibition began 10-15 ms after the minimum corticospinal conduction time to the muscle, and lasted for about 30 ms. The depth of inhibition was approximately proportional to the level of on-going EMG. A similar period of inhibition was also observed in the forearm flexor muscles, but in biceps it was less clear and sometimes preceded by excitation.8. The interhemispheric inhibition described in these experiments is probably produced via a transcallosal pathway.