Figure 3.
Effects of placebo on the activation of μ-opioid receptor-mediated neurotransmission. After correction for multiple comparisons, significant effects of placebo on the activation of the μ-opioid system (n = 14) were detected in the left DLPFC (x, y, z peak coordinates, -36, 13, 39; cluster size, 1403 mm3; z score, 4.27; p < 0.0001), rostral anterior cingulate (RACing; x, y, z, 14, 49, 13; cluster size, 3193 mm3, z score, 4.18; p < 0.0001), left nucleus accumbens (NAcc; x, y, z, -7, 11, -11; cluster size, 1332 mm3; z score, 4.83; p < 0.0001), and right anterior insula (Ins; x, y, z, 41, 10, -17; cluster size, 844 mm3; z score, 4.15; p < 0.05). The posterior right insula achieved subthreshold levels of significance (44, -15, 4; cluster size, 732 mm3; z score, 3.81; p < 0.0001 uncorrected for multiple comparisons). z scores of statistical significance are represented by the pseudocolor scale on the right side of the image and are superimposed over an anatomically standardized MRI image in coronal views. The left side of the axial and coronal images corresponds to the right side of the body (contralateral to pain) (radiological convention).