It is generally believed that the placebo response can elicit an analgesic effect, whilst the nocebo response can elicit a hyperalgesia effect in pain. Placebo analgesia and nocebo hyperalgesia effects are increasing concerns for researchers. Growing evidence suggests personality differences have an impact on both placebo and nocebo effects. However, previous studies have not reached a unified conclusion. We designed this study to explore the personality differences of functional magnetic resonance imaging (fMRI) signals in placebo response and nocebo response by using psychophysiological interaction (PPI) analysis. 30 healthy subjects underwent conditioning induction training to establish expectations of placebo effect and nocebo effect, and then, all subjects completed the following experimental procedures: (1) baseline scanning, (2) acute pain model establishment, (3) pain status scanning, and (4) pseudorandom scanning of block design of placebo response or nocebo response. Behavioral data were collected after each scan. The results of this study showed that (1) there were significant differences of VAS placebo intervention between the extrovert group and the introvert group (); (2) there were significant differences of VAS nocebo intervention between the extrovert group and the introvert group (); (3) there were significant differences between the VAS placebo intervention and VAS pain status (baseline) in both the extrovert group () and the introvert group (); (4) there were significant differences between the VAS nocebo intervention and VAS pain status (baseline) in both the extrovert group () and the introvert group (). Moreover, there were significant differences in the brain network for placebo and nocebo responses between different personalities. We found that (1) deactivation differences of the pain-related network and limbic system play an important role in personality differences associated with placebo analgesia and (2) differences of control of anxiety and activation of dorsolateral prefrontal cortex may cause the personality differences observed in nocebo hyperalgesia.

中文翻译：

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安慰剂镇痛和 Nocebo 痛觉过敏中脑网络的个性差异：fMRI 中的心理生理相互作用 (PPI) 方法

一般认为安慰剂反应可引起镇痛作用，而反安慰剂反应可引起疼痛的痛觉过敏作用。安慰剂镇痛和反安慰剂痛觉过敏效应越来越受到研究人员的关注。越来越多的证据表明，性格差异对安慰剂和反安慰剂效应都有影响。然而，以往的研究并没有得出统一的结论。我们设计这项研究是为了通过使用心理生理学相互作用 (PPI) 分析来探索功能性磁共振成像 (fMRI) 信号在安慰剂反应和反安慰剂反应中的个性差异。30名健康受试者接受调理诱导训练，建立安慰剂效应和反安慰剂效应的预期，然后，所有受试者完成以下实验程序：（1）基线扫描，(2)急性疼痛模型建立，(3)疼痛状态扫描，(4)安慰剂反应或反安慰剂反应区组设计的伪随机扫描。每次扫描后收集行为数据。本研究结果表明：（1）外向组与内向组在VAS安慰剂干预方面存在显着差异（); (2)外向组与内向组VAS nocebo干预存在显着差异(); (3) 外向组 ()和内向组 (); (4) 外向组（)和内向组 (）。此外，不同性格之间安慰剂和反安慰剂反应的大脑网络存在显着差异。我们发现（1）疼痛相关网络和边缘系统的失活差异在与安慰剂镇痛相关的人格差异中起重要作用；（2）焦虑控制和背外侧前额叶皮层激活的差异可能导致在反安慰剂痛觉过敏。