The time course of changes in motor cortex excitability associated with voluntary movement
The time course of changes in motor cortex excitability associated with voluntary movement
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DOI：
10.1017/s0317167100000196
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发表时间：
1999-08-01
影响因子：
3
通讯作者：
Hallett, M
中科院分区：
文献类型：
--
作者：
Chen, R;Hallett, M
运动皮层的兴奋性在随意运动之前和之后受到调节。经颅磁刺激研究表明，对于简单反应时间和自定进度运动，肌电图开始前约 80 毫秒和 100 毫秒，皮质脊髓兴奋性分别增加。随意运动后，肌电图偏移后，皮质脊髓兴奋性增加有两个阶段：从 0 到约 100 毫秒以及从约 100 到 160 毫秒。第一阶段可能对应于运动相关皮层电位研究中运动电位的额叶峰值和脑磁图（MEG）研究中运动诱发磁场I（MEFI），并且可能代表运动皮层输出减少低于脊髓运动神经元激活所需的输出的时间，但仍高于静息水平。皮质脊髓兴奋性增加的第二阶段可能是由于外周本体感觉输入所致，也可能是集中编程的，代表阈下第二次激动剂爆发。这可能对应于MEG研究中的MEFII。 EMG 偏移后约 500 至 1,000 毫秒，皮质脊髓兴奋性降低至基线水平以下，类似于运动皮质节律功率（事件相关同步，ERS）增加的时间。类似地，正中神经刺激后运动皮层节律的 ERS 时运动皮层兴奋性降低。这些发现支持这样的假设：ERS 代表皮质的不活跃、空闲状态。在帕金森病和肌张力障碍等运动障碍中，皮质激活的时间过程是异常的，反映了运动准备和运动后皮质兴奋性的异常。
The excitability of the motor cortex is modulated before and after voluntary movements. Transcranial magnetic stimulation studies showed increased corticospinal excitability from about 80 and 100 ms before EMG onset for simple reaction time and self-paced movements, respectively. Following voluntary movements, there are two phases of increased corticospinal excitability from 0 to approximately 100 ms and from approximately 100 to 160 ms after EMG offset. The first phase may correspond to the frontal peak of motor potential in movement-related cortical potentials studies and the movement-evoked magnetic field I (MEFI) in magnetoencephalographic (MEG) studies, and likely represents a time when decreasing output from the motor cortex falls below that required for activation of spinal motoneurons, but is still above resting levels. The second phase of increased corticospinal excitability may be due to peripheral proprioceptive inputs or may be centrally programmed representing a subthreshold, second agonist burst. This may correspond to the MEFII in MEG studies. Corticospinal excitability was reduced below baseline levels from about 500 to 1,000 ms after EMG offset, similar to the timing of increase in the power (event-related synchronization, ERS) of motor cortical rhythm. Similarly, motor cortex excitability is reduced at the time of ERS of motor cortical rhythm following median nerve stimulation. These findings support the hypothesis that ERS represents an inactive, idling state of the cortex. The time course of cortical activation is abnormal in movement disorders such as Parkinson's disease and dystonia, reflecting abnormalities in both movement preparation and in cortical excitability following movement.