Abstract
Musical analgesia, also commonly referred to as audio-analgesia or music-induced analgesia, is the phenomenon of experiencing pain relief while listening to music. Music therapy employs musical analgesia in clinical settings as an inexpensive, drug-free alternative or adjunct treatment for pain. Experimental studies have explored possible mechanisms of action with the aim to increase the effectiveness and validity of music therapy. However, few studies have attempted to disentangle how music’s capacity as a reward and our inherent expectations for music’s effects on our subjective state are potential driving forces of the music analgesic effect. Because both reward and expectancy are regulated by endogenous μ-opioids, we ask whether music-induced analgesia is mediated by the endogenous opioid system and whether the expectation of pain relief is a driving force of this effect. To answer this question, a randomized, placebo-controlled study design utilizing full μ-opioid blockade is planned. In a non-pharmacological pilot study, study protocols and procedures were developed to establish the efficacy of our design and conduct an informed sensitivity analysis to determine sample size for the future study. A novel expectation manipulation was developed to determine how expectations for pain relief during music listening impact a musical analgesic effect. Subjective state was captured by self-reported measures of affect, arousal, musical enjoyment and physiological state by pupil size. Thirty-two participants were tested in the lab with the full experimental task and procedures, and 129 participants were surveyed online to validate our expectation manipulation. In line with previous research, preferred music, as compared to noise, was successful in inducing an analgesic effect. Furthermore, reward was a significant moderator of the analgesic effect. Decreased pain and increased musical enjoyment during music listening compared to noise was reflected only by subjective ratings, not pupil size. The expectation manipulation was found to successfully alter expectations in an online validation survey, but we were unable to replicate the success of the manipulation in the smaller pilot. However, participants' expectations for pain relief during music listening were correlated with their pain ratings in the experiment. The methods and results presented in this thesis will be used to inform a future study investigating the role of reward, expectation, and the μ-opioid system as mechanisms of musical analgesia.