Fig. 3

Effect of Expectation − Effectiveness classification on µ-opioid system activation. Left: significant effects of Expectation − Effectiveness comparisons on Δ in µ-opioid BP_ND during placebo administration were found in (P < 0.001, k > 10 voxels) in the left subgenual, rostral and dorsal anterior cingulate cortex (sgACC, rACC, dACC), the OFC bilaterally and the hippocampus/amygdala (AMYG) bilaterally, the posterior hippocampus bilaterally, the left thalamus and the anterior insula bilaterally (INS). Upper right: effect of expectation-effectiveness comparisons on Δ regional in µ-opioid BP_ND during placebo administration in the dACC. Lower right: placebo-induced activation of µ-opioid neurotransmission in the dACC was correlated with reductions in pain ratings after placebo administration as measured by the change in MPQ total scores (MPQ: r = 0.4, P = 0.001).