On the other hand, in the only study that has examined adultage differences in DA release during cognitive performance, we found evidence for a less modifiable DA system in the old (Karlssonet al., 2009). In that study, DA binding in younger and older adults was determined using PET while subjects were engaged in a task that taxes interference resolution and in a control condition (Bushet al., 2003). As displayed in Fig. 9, whereas the young showed clear decreases in ligand binding to DA receptors in sensorimotor, asso-ciative, and limbic striatum (suggestive of DA release) during the interference relative to the control task, the old did not. Thus, the verdict is still out as to whether training-induced DA release can bedemonstrated in older adults. Knowledge pertaining to this issue could be obtained by investigating older adults during the same training conditions as used by Bäckman et al. (2011).