Fig. 3.

Individual CP data for the (A) MPFC and (B) right IFG. (Left) CP maps from two representative individuals. Maps were thresholded according to a per-voxel critical value for statistical significance (P < 0.05) obtained by a permutation test. The color bar indicates CP of individual voxels, which were the average value from the separate analyses with neutral and happy trials (see Methods). (Center) Choice-related ROC curve for the peak voxel of the activation (Left) when considering neutral trials only (red) and happy trials only (green). The x axis corresponds to the probability that fMRI magnitude in no-fear-response trials exceeds a criterion response magnitude; the y axis corresponds to the probability that fMRI amplitude in fear-response trials exceeds the same criterion. The ROC curve is determined by sliding the criterion value. The CP corresponds to the area under the ROC curve. The blue line (y = x) represents chance performance (area = 0.5), and departures from it indicate the possibility of distinguishing between the two trial types. In particular, ROC curves above the identity line indicate that responses during fear-response trials were consistently greater than responses during no-fear-response trials. Peak MPFC voxel coordinates: red and green curves, x = 0, y = 24, and y = 42; right IFG: red curve, x = 49, y = 17, and z = 3; green curve, x = 53, y = 15, and z = 3. (Right) Distribution of peak CP values for individual subjects for the (A) MPFC and (B) right IFG regions. Again, values were averaged from the analyses with neutral and happy trials.