Brainstem’s Role in Placebo and Pain Perception Highlighted Interview with:
Lewis Crawford, B.Sci (Hons), PhD Candidate 
Neural Imaging Laboratory | Faculty of Medicine and Health
University of Sydney  What is the background for this study?  What are the main findings?

Response: This study was performed as a means to accurately and robustly define the areas of the brainstem responsible for alleviating and enhancing pain via conditioning and expectation alone, that is, the phenomena of placebo analgesia and nocebo hyperalgesia. The reason we were able to do this was by being able to access a 7-tesla ultra-high field MRI, one of only two in Australia, that allowed us to resolve the small nuclei in the brainstem which make up descending analgesic circuitry (they carry signals from your brain to your spinal cord).

We found that a central pathway, comprised of the midbrain Periaqueductal Gray (PAG) and Rostral Ventromedial Medulla (RVM), acted during both phenomena, however in opposite ways. We also identified several other nuclei as playing a role in the modulation of pain which, prior to this study, had not been explored or suggested to play a role in this context. We believe that the brainstem circuitry we defined here enables further research into mechanisms responsible for analgesia and hyperalgesia and will promote further investigation into brainstem function in humans. 

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