Discipline of Physiology, School of Medical Science, The University of Adelaide, Adelaide, SA, Australia.
Eur J Neurosci. 2011 May;33(10):1916-24. doi: 10.1111/j.1460-9568.2011.07673.x. Epub 2011 Apr 13.
Repetitive transcranial magnetic stimulation paradigms such as continuous theta burst stimulation (cTBS) induce long-term potentiation- and long-term depression-like plasticity in the human motor cortex. However, responses to cTBS are highly variable and may depend on the activity of the cortex at the time of stimulation. We investigated whether power in different electroencephalogram (EEG) frequency bands predicted the response to subsequent cTBS, and conversely whether cTBS had after-effects on the EEG. cTBS may utilize similar mechanisms of plasticity to motor learning; thus, we conducted a parallel set of experiments to test whether ongoing electroencephalography could predict performance of a visuomotor training task, and whether training itself had effects on the EEG. Motor evoked potentials (MEPs) provided an index of cortical excitability pre- and post-intervention. The EEG was recorded over the motor cortex pre- and post-intervention, and power spectra were computed. cTBS reduced MEP amplitudes; however, baseline power in the delta, theta, alpha or beta frequencies did not predict responses to cTBS or learning of the visuomotor training task. cTBS had no effect on delta, theta, alpha or beta power. In contrast, there was an increase in alpha power following visuomotor training that was positively correlated with changes in MEP amplitude post-training. The results suggest that the EEG is not a useful state-marker for predicting responses to plasticity-inducing paradigms. The correlation between alpha power and changes in corticospinal excitability following visuomotor training requires further investigation, but may be related to disengagement of the somatosensory system important for motor memory consolidation.
重复经颅磁刺激范式，如连续 theta 爆发刺激（cTBS），可在人类运动皮层诱导长时程增强和长时程抑制样可塑性。然而，cTBS 的反应具有高度可变性，可能取决于刺激时皮层的活动。我们研究了不同脑电图（EEG）频段的功率是否可以预测随后的 cTBS 反应，反之亦然，cTBS 是否对 EEG 有后续影响。cTBS 可能利用与运动学习类似的可塑性机制；因此，我们进行了一组平行实验，以测试正在进行的脑电图是否可以预测视觉运动训练任务的表现，以及训练本身是否对 EEG 有影响。运动诱发电位（MEP）提供了干预前后皮质兴奋性的指标。在干预前后记录运动皮层的脑电图，并计算功率谱。cTBS 降低了 MEP 幅度；然而，delta、theta、alpha 或 beta 频率的基线功率并不能预测 cTBS 反应或视觉运动训练任务的学习。cTBS 对 delta、theta、alpha 或 beta 功率没有影响。相比之下，视觉运动训练后 alpha 功率增加，与训练后 MEP 幅度的变化呈正相关。结果表明，脑电图不是预测诱导可塑性范式反应的有用状态标志物。视觉运动训练后 alpha 功率与皮质脊髓兴奋性变化之间的相关性需要进一步研究，但可能与运动记忆巩固过程中对体感系统的脱离有关。
