Neuron
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Expectations, positive or negative, are modulating factors influencing behavior. They are also thought to underlie placebo effects, impacting perceptions and biological processes. ⋯ In additional functional MRI studies, the expectation of monetary gain increased NAC synaptic activity in a manner proportional to placebo-induced DA release, anticipated effects, perception-anticipation differentials, and actual placebo effects. Individual variations in NAC response to reward expectation accounted for 28% of the variance in the formation of placebo analgesia.