Brown P
National Hospital for Neurology, Institute of Neurology, London, UK.
Clin Neurosci. 1995;3(4):193-7.
The study of cortical myoclonus affords an insight into both the spatiotemporal organization of the human sensorimotor cortex and the nature of descending motor signals. Cortical activity tends to be rhythmic, whether in response to peripheral stimulation or intended movement. This activity leads to a series of descending motor discharges and a train of electromyographic bursts, with a frequency of around 50 Hz. Each descending motor discharge consists of a brief series of synchronous volleys, separated by 3 to 6 ms. Such a repetitive pattern of activity takes advantage of the additive facilitation seen with high-frequency inputs to the spinal motoneurone, so that movement is ensured. In health, cortical motor activity is focused and tempered by inhibitory inputs, both local and far afield. Studies in patients have highlighted two forms of inhibition, ipsilateral cortical and transcallosal, which are reduced in those cases with more extensive jerks. This lack of inhibition facilitates the transcallosal and cortical spread of myoclonic activity responsible for bilateral and generalized myoclonic jerks.
对皮质肌阵挛的研究有助于深入了解人类感觉运动皮质的时空组织以及下行运动信号的本质。无论是对外周刺激的反应还是意向性运动，皮质活动往往具有节律性。这种活动会导致一系列下行运动放电和一连串肌电图爆发，频率约为50赫兹。每次下行运动放电由一系列短暂的同步群放电组成，间隔为3至6毫秒。这种重复的活动模式利用了脊髓运动神经元高频输入时出现的相加易化作用，从而确保运动的发生。在健康状态下，皮质运动活动受到局部和远处抑制性输入的调节和限制。对患者的研究突出了两种抑制形式，即同侧皮质抑制和胼胝体抑制，在肌阵挛发作更广泛的病例中，这两种抑制作用会减弱。这种抑制作用的缺乏促进了导致双侧和全身性肌阵挛抽搐的肌阵挛活动在胼胝体和皮质的扩散。
