Placebo analgesia: psychological and neurobiological mechanisms.

National Center for Complementary and Alternative Medicine (NCCAM), National Institute of Mental Health (NIMH) and Clinical Center, Department of Bioethics, National Institutes of Health (NIH), Bethesda, MD, USA Outpatient Clinic of Behavior Therapy, Department of Psychology, University of Hamburg, Hamburg, Germany Department of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany NeuroImage Nord, Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany