Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Nova Scotia Health Authority, Halifax, NS, Canada.
Int Rev Neurobiol. 2018;139:233-253. doi: 10.1016/bs.irn.2018.07.017. Epub 2018 Aug 6.
Why pain can be relieved with placebos is heavily debated. The term "placebo effect," implies that the placebo treatment induces pain relief which is imprecise because it is the mental cueing to the context of treatment and not the placebo itself that can reduce pain. This essay reverts to fundamentals of perception that have been used to explain how context generates predictions that can in turn effect the process of processing, organizing and interpreting of sensory inputs received from the periphery. We reinterpret placebo effect as a neurobiological phenomenon that occurs through the process of reward and aversive learning. The brain uses learnt information to generate predictions. The perceptual processes adjust the experience of pain to fit with the predictions generated from prior information. Placebo effect is thus understandably a result of the expectations and mental states that result from engaging in the process of treatment. These processes have teleological roots in ancient medicine and are the context that produces these responses is transforming with the evolution of modern medicine. Thus, when placebo effect is observed, the potent agent that induces pain reduction is not the placebo itself, but the mental cueing to the context of taking treatment.
为什么安慰剂可以缓解疼痛这个问题存在很大争议。“安慰剂效应”这个术语暗示，安慰剂治疗会引起疼痛缓解，但这种说法并不准确，因为减轻疼痛的是治疗环境的心理暗示，而不是安慰剂本身。本文回归到感知的基本原理，这些原理被用来解释环境如何产生预测，而这些预测反过来又会影响从外围接收的感觉输入的处理、组织和解释过程。我们将安慰剂效应重新解释为一种神经生物学现象，它通过奖励和厌恶学习过程发生。大脑利用所学信息生成预测。感知过程会调整疼痛体验，以适应从先前信息生成的预测。因此，安慰剂效应是参与治疗过程所产生的期望和心理状态的结果。这些过程在古代医学中具有目的论根源，产生这些反应的环境随着现代医学的发展而发生变化。因此，当观察到安慰剂效应时，引起疼痛减轻的有效药物不是安慰剂本身，而是接受治疗的环境的心理暗示。
