Fig. 3.

Response of 38 healthy trustee brains and 55 BPD trustee brains to level of cooperation. (Top) Results of both between- and within-group GLM analyses identified cortical regions with greater response to small investments (I ≤ $5) relative to large investments (I > $10). All significant voxels are conservatively corrected using false-discovery rate procedures to the P < 0.05 level in yellow; P < 0.10 in orange (see tables S3 to S5). (Bottom) Percent change in hemodynamic signal was averaged from the 115 most significant voxels identified in the group-level GLM (top left and table S3) during the 4- to 8-s period following the revelation of investment. The means ± SE of the resulting signal are plotted in $4 bins. Responses in bilateral anterior insula in healthy trustees scale strongly and negatively with the size of investment (r = −0.97; bottom middle). In contrast, similar analyses in individuals with BPD showed no such relation.