Novel designs and paradigms to study the placebo response in gastroenterology

Expectancy and learning as the two best-characterized principle mechanisms that mediate placebo and nocebo effects. Learning processes include classical conditioning, instrumental learning and social observation. These processes shape expectations about a treatment involving both emotions (state anxiety, fear, hope) and cognitions. They are centrally mediated, involve multiple brain regions and influence gastrointestinal sensory and motor functions along the bidirectional brain-gut axis. The entire psychosocial treatment context, including the factual information that is provided to the patient about a treatment, the quantity and quality of the patient-provider communication and features of the medical setting, shape placebo and nocebo responses through learning and expectation (modified from [1]).