title: Brain Mechanisms of the Placebo Effect: An Affective Appraisal Account.
abstract: Placebos are sham medical treatments. Nonetheless, they can have substantial effects on clinical outcomes. Placebos depend on a person's psychological and brain responses to the treatment context, which influence appraisals of future well-being. Appraisals are flexible cognitive evaluations of the personal meaning of events and situations that can directly impact symptoms and physiology. They also shape associative learning processes by guiding what is learned from experience. Appraisals are supported by a core network of brain regions associated with the default mode network involved in self-generated emotion, self-evaluation, thinking about the future, social cognition, and valuation of rewards and punishment. Placebo treatments for acute pain and a range of clinical conditions engage this same network of regions, suggesting that placebos affect behavior and physiology by changing how a person evaluates their future well-being and the personal significance of their symptoms.
authors.affiliation: Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309.
authors.forename: Yoni K
authors.initials: YK
authors.lastname: Ashar
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Chang
authors.affiliation: Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309.|Institute of Cognitive Science, University of Colorado, Boulder, Colorado 80309; email: tor.wager@colorado.edu.
authors.forename: Tor D
authors.initials: TD
authors.lastname: Wager
mesh_terms: D001921:Brain / Q000503:physiopathology*; D004644:Emotions / Q000502:physiology*; D006801:Humans; D001523:Mental Disorders / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D015990:Placebo Effect
keywords: Parkinson's disease; default mode; emotion; expectation; mood disorders; pain