Fig. 2. Z-score significance map of normalized increases in regional CBF in response to intravenous yohimbine (yohimbine scan minus placebo scan). Normalization was performed by dividing each voxel value by whole brain value. 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 = 5.50). Right and left are reversed. Map is overlaid on a generic MRI template to provide anatomical orientation.