Kazennikov Oleg, Solopova Irina, Talis Vera, Grishin Alexander, Ioffe Marat
Institute for Information Transmission Problems, Russian Academy of Science, Bolshoy Karetny, 19, Moscow 127994, Russia.
Neurosci Lett. 2005 Aug 5;383(3):246-50. doi: 10.1016/j.neulet.2005.04.005. Epub 2005 Apr 26.
Transcranial magnetic brain stimulation (TMS) was used to assess the influence of the corticospinal system on motor output during forearm unloading in humans. Unloading was obtained either "passively" by the experimenter, or "actively" with the subjects' own contralateral arm. Anticipatory postural adjustments consisted of changes in the activity of a forearm flexor muscle prior to active unloading of the limb and acted to stabilize the forearm position. Motor evoked potentials (MEPs) were recorded in the forearm flexor at different times during active and passive unloading, static forearm loading, and during lifting of an equivalent weight by the contralateral arm while the ipsilateral forearm was statically loaded and held stationary. In active unloading, MEP amplitude decreased with the decrease of muscle activity. Passive unloading resulted in a similar decrease of MEP as with active unloading. During stationary forearm loading, the change in MEP corresponded to the degree of loading. If during static loading the contralateral arm has lifted a separate, equivalent weight, the amplitude of MEP decreased. A possible role of direct corticospinal volley and the motor command mediated by subcortical structures in anticipatory postural adjustments is discussed.
经颅磁刺激（TMS）被用于评估皮质脊髓系统对人体前臂卸载过程中运动输出的影响。卸载可由实验者“被动”实现，也可由受试者自身对侧手臂“主动”完成。预期姿势调整包括在肢体主动卸载之前前臂屈肌活动的变化，其作用是稳定前臂位置。在主动和被动卸载、静态前臂负重以及对侧手臂提起同等重量而同侧前臂静态负重并保持静止的不同阶段，记录前臂屈肌的运动诱发电位（MEP）。在主动卸载过程中，MEP波幅随肌肉活动的减少而降低。被动卸载导致的MEP下降与主动卸载相似。在前臂静态负重期间，MEP的变化与负重程度相对应。如果在静态负重时对侧手臂提起了一个单独的同等重量物体，MEP波幅会降低。本文还讨论了皮质脊髓直接放电和皮质下结构介导的运动指令在预期姿势调整中的可能作用。
