The periaqueductal gray and Bayesian integration in placebo analgesia

In placebo hypoalgesia research, the strength of treatment expectations and experiences are key components. However, the reliability or precision of expectations had been mostly ignored although being a likely source for interindividual differences. In the present study, we adopted a Bayesian framew...

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Bibliographic Details
Published in:eLife 2018-03, Vol.7
Main Authors: Grahl, Arvina, Onat, Selim, Büchel, Christian
Format: Article
Language:English
Subjects:
Analgesia
Bayesian
Bayesian analysis
Brain stem
Clinical outcomes
Computational and Systems Biology
fMRI
Functional magnetic resonance imaging
Integration
Medulla oblongata
Neuroscience
PAG
Pain
Pain perception
Perceptions
Periaqueductal gray area
placebo analgesia
Placebo effect
Placebos
precision
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Summary:In placebo hypoalgesia research, the strength of treatment expectations and experiences are key components. However, the reliability or precision of expectations had been mostly ignored although being a likely source for interindividual differences. In the present study, we adopted a Bayesian framework, naturally combining expectation magnitudes and precisions. This postulates that expectations (prior) are integrated with incoming nociceptive information (likelihood) and both are weighted by their relative precision to form the pain percept and placebo effect. Sixty-two healthy subjects received heat pain during fMRI. Placebo effects were more pronounced in subjects with more precise treatment expectations and correlated positively with the relative precision of the prior expectation. Neural correlates of this precision were observed in the periaqueductal gray and the rostral ventromedial medulla, indicating that already at the level of the brainstem the precision of an expectation can influence pain perception presenting strong evidence for Bayesian integration in placebo hypoalgesia.
ISSN:2050-084X
2050-084X
DOI:10.7554/eLife.32930