Pain perception is closely tied to the brain's anticipatory processes, particularly involving the suppression of sensorimotor α-oscillations, which reflect the system's readiness for incoming pain. Higher sensorimotor α-oscillation levels are correlated with lower pain sensitivity. Alpha transcranial alternating current stimulation (α-tACS) can enhance these oscillations, potentially reducing pain perception, with effects that may be sustained and influenced by the certainty of pain expectations. Hence, this study investigated the immediate and sustained effects of α-tACS on pain anticipation and perception, focusing on how these effects are shaped by the certainty of expectations. In a double-blind, sham-controlled design, 80 healthy participants underwent a 20-minute session of real or sham α-tACS over the right sensorimotor region. Behavioral and neural responses related to pain anticipation and perception were recorded before, immediately after, and 30 minutes poststimulation under both certain and uncertain conditions. Compared with sham stimulation, real α-tACS disrupted the habituation of laser-evoked potentials (N2-P2 complex), particularly under certain expectations, with effects persisting 30 minutes poststimulation. In anticipatory brain oscillations, real α-tACS enhanced somatosensory α1-oscillations and increased midfrontal θ-oscillations in conditions of certainty, with θ-oscillation modulation showing sustained effects. Mediation analysis revealed that α-tACS reduced pain reactivity by enhancing somatosensory α1-oscillations but increased pain reactivity through the enhancement of midfrontal θ-oscillations, with the latter effect being more pronounced. These findings suggest that while α-tACS may provide pain relief through somatosensory α-oscillation augmentation, its stronger and longer-lasting impact on midfrontal θ-oscillations could lead to hyperalgesia, particularly in the context of certain pain expectations.

中文翻译：

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α 经颅交流电刺激以上下文依赖性方式调节疼痛预期和感知。


疼痛感知与大脑的预期过程密切相关，特别是涉及抑制感觉运动α振荡，这反映了系统对即将到来的疼痛的准备情况。较高的感觉运动 α 振荡水平与较低的疼痛敏感性相关。α 经颅交流电刺激 （α-tACS） 可以增强这些振荡，可能减少疼痛感知，其效果可能会持续并受疼痛预期确定性的影响。因此，本研究调查了 α-tACS 对疼痛预期和感知的直接和持续影响，重点关注这些影响如何受到期望确定性的影响。在双盲、假对照设计中，80 名健康参与者在右侧感觉运动区域接受了 20 分钟的真实或假 α-tACS 治疗。在确定和不确定的条件下，在刺激之前、之后和之后 30 分钟记录与疼痛预期和感知相关的行为和神经反应。与假刺激相比，真正的 α-tACS 破坏了激光诱发电位 （N2-P2 复合物） 的习惯化，特别是在某些预期下，效果在刺激后持续 30 分钟。在预期脑振荡中，真正的 α-tACS 在确定的条件下增强了体感 α1 振荡并增加了额中部 θ 振荡，θ 振荡调制显示出持续的效果。介导分析显示，α-tACS 通过增强体感 α1 振荡来降低疼痛反应性，但通过增强额中 θ 振荡来增加疼痛反应性，后者的效果更为明显。 这些发现表明，虽然 α-tACS 可能通过体感 α 振荡增强来缓解疼痛，但其对额中 θ 振荡更强和更持久的影响可能导致痛觉过敏，尤其是在某些疼痛预期的情况下。