School of Medicine, University of Manchester, Manchester, United Kingdom.
PLoS One. 2013 Oct 11;8(10):e78278. doi: 10.1371/journal.pone.0078278. eCollection 2013.
The lack of clear understanding of the pathophysiology of chronic pain could explain why we currently have only a few effective treatments. Understanding how pain relief is realised during placebo analgesia could help develop improved treatments for chronic pain. Here, we tested whether experimental placebo analgesia was associated with altered resting-state cortical activity in the alpha frequency band of the electroencephalogram (EEG). Alpha oscillations have been shown to be influenced by top-down processes, which are thought to underpin the placebo response. Seventy-three healthy volunteers, split into placebo or control groups, took part in a well-established experimental placebo procedure involving treatment with a sham analgesic cream. We recorded ongoing (resting) EEG activity before, during, and after the sham treatment. We show that resting alpha activity is modified by placebo analgesia. Post-treatment, alpha activity increased significantly in the placebo group only (p < 0.001). Source analysis suggested that this alpha activity might have been generated in medial components of the pain network, including dorsal anterior cingulate cortex, medial prefrontal cortex, and left insula. These changes are consistent with a cognitive state of pain expectancy, a key driver of the placebo analgesic response. The manipulation of alpha activity may therefore present an exciting avenue for the development of treatments that directly alter endogenous processes to better control pain.
对慢性疼痛病理生理学缺乏清晰认识，可能可以解释为什么我们目前仅有少数有效的治疗方法。了解安慰剂镇痛过程中是如何实现缓解疼痛的，可能有助于开发治疗慢性疼痛的改进方法。在这里，我们测试了实验性安慰剂镇痛是否与脑电图（EEG）的 alpha 频段静息状态皮质活动的改变有关。已经表明 alpha 振荡受自上而下的过程影响，这些过程被认为是安慰剂反应的基础。73 名健康志愿者分为安慰剂组或对照组，参与了一项成熟的实验性安慰剂程序，涉及使用假镇痛霜进行治疗。我们在 sham 治疗之前、期间和之后记录了持续的（静息）EEG 活动。我们表明，安慰剂镇痛会改变静息时的 alpha 活动。治疗后，只有安慰剂组的 alpha 活动显著增加（p < 0.001）。源分析表明，这种 alpha 活动可能是在疼痛网络的内侧成分中产生的，包括背侧前扣带皮层、内侧前额叶皮层和左侧脑岛。这些变化与疼痛预期的认知状态一致，这是安慰剂镇痛反应的关键驱动因素。因此，alpha 活动的操纵可能为开发直接改变内源性过程以更好地控制疼痛的治疗方法提供了一个令人兴奋的途径。
