Fig. 2. Categorical effect of fear extinction and correlation between baseline anandamide (AEA) and neural extinction signalling.

A Brain regions with significant effects of fear extinction learning modelled as an exponentially decaying signal. Significance (whole-brain analysis) was assessed at p < 0.001 (voxel level) and p < 0.05 (cluster level, FWE-corrected, corresponding to at least 193 voxels). The statistical parametric map was superimposed on coronal and sagittal sections of the group averaged T1 image. For a statistically reliable inference of neural extinction learning, please see the summary tabulated in Table 1. B Whole-brain regression analysis: anandamide (AEA) baseline levels correlated positively with the degree of extinction learning on day 2 in the dorsal anterior cingulate cortex (dACC) and right anterior insula (AI). Significance was assessed at p < 0.001 at voxel level and p < 0.05 at cluster level resulting in at least 144 continuous voxels. Scatter plots refer to the voxel with the highest correlation coefficient. For demonstration purposes, fMRI sectional views were extracted from more conservative analyses with smaller cluster sizes. Coordinates refer to MNI space. L left, R right.