Across participants, the pattern of SWM relative to vigilance was consistent with existing literature (Barch et al., 1997; Courtney et al., 1998; D’Esposito et al., 1998; Jonides et al., 1993; Smith and Jonides, 1998), involving bilateral dorsolateral prefrontal and parietal cortices activating to SWM blocks, and medial frontal and cingulate regions activating to vigilance blocks (see Table 3). A hierarchical regression determined whether FH density would predict SWM relative to vigilance response in the 15 areas of interest that reliably activated to the task. Task-correlated motion (roll and yaw) parameters were entered on step 1, and centered FH density was entered on step 2. Considering a Bonferroni correction for the number of regressions evaluated (α = 0.05/15 = 0.003), greater FH density was related to decreased SWM response relative to vigilance in a region encompassing bilateral cingulate, posterior cingulate, and extending into the medial frontal gyri at a trend level, above and beyond effects of motion [F (3,66) = 4.26, p = 0.008; R2Δ = 7%, β = 0.28, p = 0.03] (see Fig. 2).
