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Related Experiment Video

Updated: Jul 13, 2026

How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants

How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants

Published on: December 14, 2014

Individual differences in reward responding explain placebo-induced expectations and effects.

David J Scott¹, Christian S Stohler, Christine M Egnatuk

¹Department of Psychiatry and Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-0720, USA.

|July 21, 2007

Summary

Expectations influence behavior and placebo effects. The nucleus accumbens (NAC) dopamine release during placebo administration is linked to anticipated effects and placebo analgesia development.

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Area of Science:

Neuroscience
Psychology
Pharmacology

Background:

Expectations modulate behavior and are implicated in placebo effects, influencing perceptions and biological processes.
The nucleus accumbens (NAC) is a key brain region for processing reward expectation.

Purpose of the Study:

To investigate the role of the nucleus accumbens (NAC) in the formation of placebo responses.
To examine the relationship between NAC dopamine (DA) release, reward expectation, and placebo effects in humans.

Main Methods:

Functional molecular imaging and functional MRI (fMRI) were used in healthy human subjects.
Researchers measured NAC dopamine release and synaptic activity in response to placebo administration and monetary reward expectation.

Main Results:

Placebo administration activated NAC dopamine release, correlating with anticipated effects and perception-anticipation mismatches.
Monetary reward expectation increased NAC synaptic activity, proportionally linked to placebo-induced DA release and placebo effects.
Individual differences in NAC response to reward expectation explained 28% of the variance in placebo analgesia.

Conclusions:

The nucleus accumbens plays a critical role in the neural mechanisms underlying placebo effects.
Dopamine signaling in the NAC, driven by reward expectation, is a key factor in the development of placebo analgesia.