FMRI correlates of the WAIS–III Symbol Search subtest

Functional magnetic resonance imaging (FMRI) experiments frequently administer substantially adapted cognitive tests. This study was designed to identify FMRI correlates of a well-standardized clinical measure presented with minor adaptations. We administered the WAIS–III Symbol Search (SS) and a visuospatial control task to fifteen adults during FMRI. SS-related brain activity was identified, followed by analyses of activity related to performance level. Compared to the control task, SS was associated with greater activity in bilateral medial occipital, occipitoparietal, occipitotemporal, parietal, and dorsolateral prefrontal cortices (DLPFC). Across both tasks, slower processing speed was also related to greater activity in these areas, except right DLPFC. Greater activity in left DLPFC was specifically related to slower processing speed during SS. Performance was consistent with education levels. Findings suggest that SS performance involves regions associated with executive and visual processing. Furthermore, slower SS performance was related to greater recruitment of left hemisphere regions associated with executive function in other studies. (JINS, 2005, 11, 471–476.)