Fig. 3.

Effects of age of first use of marijuana on Tract-Based Spatial Statistics from the restricted sample of 277 unrelated marijuana users. Hot colors depict a positive relationship between age of first use and FA, i.e., earlier age of onset associated with decreased FA, and cold colors depict a negative relationship between age of first use and RD, i.e., earlier age of onset associated with increased RD. Earlier marijuana use was associated with decreased white matter coherence in the right Superior Longitudinal Fasciculus, lateral prefrontal white matter, and the anterior corpus callosum extending to the Forceps Minor. White numbers reflect MNI coordinates in the Z (axial slices), and Y (coronal slices) planes.