Opioid-independent and opioid-mediated modes of pain modulation - The Journal of Neuroscience, 2018

Pain perception is mediated by expectations and context, physiological state and reappraisal. To counteract pain, there exist opioid-dependent and –independent modes inducing analgesia in humans. The latter comprises hypnosis, mindfulness meditation and religious prayer. In this study, they assessed the effects of different pain modulators: naloxone (pain killer, opioid-dependent), mental imagery and relative relief. Mental imagery works by imaging being in a more pleasant context or finding a meaning for the painful stimulus. Relative relief is induced by telling the subject that the stimulus will be intense but a signal actually shows it as moderate.

The pain was induced by a thermode on the left forearm of participants, while subjected to either the mental imagery or relative relief task. The results showed that for participants that have not received naloxone, both pleasant imagery and relative relief reduced pain intensity ratings and increased the pleasantness of a moderate stimulus. Naloxone injection only blocked the relative relied-induced pain modulation. Altogether, this study shows that mental imagery can be a good therapeutic approach for chronic pain, as it is easy to master and induces powerful effects.

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