Over the past decade, theta-burst stimulation (TBS) has become a focus of interest in neurostimulatory research. Compared to conventional repetitive transcranial magnetic stimulation (rTMS), TBS produces more robust changes in cortical excitability (CE). There is also some evidence of an analgesic effect of the method. Previously published studies have suggested that different TBS parameters elicit opposite effects of TBS on CE. While intermittent TBS (iTBS) facilitates CE, continuous TBS (cTBS) attenuates it. However, prolonged TBS (pTBS) with twice the number of stimuli produces the opposite effect. In a double-blind, placebo-controlled, cross-over study with healthy subjects (n = 24), we investigated the effects of various pTBS (cTBS, iTBS, and placebo TBS) over the right motor cortex on CE and pain perception. Changes in resting motor thresholds (RMTs) and absolute motor-evoked potential (MEP) amplitudes were assessed before and at two time-points (0–5 min; 40–45 min) after pTBS. Tactile and thermal pain thresholds were measured before and 5 min after application. Compared to the placebo, prolonged cTBS (pcTBS) transiently increased MEP amplitudes, while no significant changes were found after prolonged iTBS. However, the facilitation of CE after pcTBS did not induce a parallel analgesic effect. We confirmed that pcTBS with twice the duration converts the conventional inhibitory effect into a facilitatory one. Despite the short-term boost of CE following pcTBS, a corresponding analgesic effect was not demonstrated. Therefore, the results indicate a more complex regulation of pain, which cannot be explained entirely by the modulation of excitability.

中文翻译：

---

运动皮层的长时间连续 Theta 爆发刺激可调节皮层兴奋性，但不会调节疼痛感

在过去的十年中，theta-burst 刺激 (TBS) 已成为神经刺激研究的热点。与传统的重复经颅磁刺激 (rTMS) 相比，TBS 会在皮质兴奋性 (CE) 方面产生更强劲的变化。还有一些证据表明该方法具有镇痛作用。先前发表的研究表明，不同的 TBS 参数会引起 TBS 对 CE 的相反影响。虽然间歇性 TBS (iTBS) 促进 CE，但连续 TBS (cTBS) 减弱它。然而，刺激次数加倍的延长 TBS (pTBS) 会产生相反的效果。在一项对健康受试者（n = 24）进行的双盲、安慰剂对照、交叉研究中，我们研究了各种 pTBS（cTBS、iTBS 和安慰剂 TBS）对右侧运动皮层对 CE 和疼痛感知的影响。在 pTBS 之前和之后的两个时间点（0-5 分钟；40-45 分钟）评估静息运动阈值 (RMT) 和绝对运动诱发电位 (MEP) 幅度的变化。在使用前和使用后 5 分钟测量触觉和热痛阈值。与安慰剂相比，延长的 cTBS (pcTBS) 瞬时增加了 MEP 振幅，而延长 iTBS 后没有发现显着变化。然而，pcTBS 后 CE 的促进并没有引起平行的镇痛作用。我们证实，具有两倍持续时间的 pcTBS 将传统的抑制作用转化为促进作用。尽管 pcTBS 后 CE 的短期增强，但没有证明相应的镇痛作用。因此，结果表明疼痛的调节更为复杂，这不能完全由兴奋性的调节来解释。