Shape analysis. 2D results of the shape analysis of the amygdala (A) and the nucleus accumbens (B) show areas that are significantly different between marijuana and control participants (left); 3D results are shown on right. Below each colorized statistical map, differences in shape were significantly associated with several drug use measures. An asterisk after the p-value in A and after the left/right color legend in B indicates a significant correlation (corrected). Please see Table 4 for significance after correcting for multiple comparisons. C, Color maps indicate bivariate correlations between modalities in the left nucleus accumbens (left). The relationship between gray matter density and shape and between gray matter density and volume differed between marijuana usersr and control participants; one asterisk indicates a trend correlation; two asterisks indicate a significant correlation (corrected). Please see Table 6 for significance after correcting for multiple comparisons. GMd, Gray matter density; Vol, volume.