Fig. 1. Z-score significance map of absolute decreases in regional CBF in response to intravenous yohimbine (placebo scan minus yohimbine scan). Scan slices are horizontal at millimeter (mm) levels above (+) or below (-) the AC-PC line as indicated. Difference in each voxel is represented by color coding. Color coding bar indicating correspondence of color to Z-score appears on the Figure (maximum Z-score = 3.50). Right and left are reversed. Map is overlaid on a generic magnetic resonance imaging (MRI) template to provide anatomical orientation.