FIGURE 1.  (A) Average unmetabolized ¹¹C-DASB fraction vs. time for baseline studies. Unlike other ligands, fraction is lower at first time point (2 min) than at second time point (12 min). (B) This lower fraction is caused by lower level of unmetabolized parent compound at 2 min than at 12 min (solid lines) in all but 5 studies (dashed lines).