Previous work investigating the utility of the default network suggests that activation in midline structures decreases in response to greater task difficulty (Greicius and Menon, 2004; Greicius et al., 2003; McKiernan et al., 2003). McKiernan et al. (2003) contrasted BOLD activation during a parametrically-manipulated short-term memory condition to response obtained during a target discrimination condition. As task demands increased, processing reserves were reallocated from default areas to regions necessary for the active condition. The authors concluded that the magnitude by which midline activation changed represented the degree to which resting state activity was inhibited to maintain successful task-relevant processing. Functional connectivity studies also support the notion that opposing activation patterns between default and higher-order cortical regions may serve to enhance performance (Greicius et al., 2003). Hampson et al. (2006) reported that increasing working memory performance positively correlated with the strength of connectivity in the default network, and proposed that lateral prefrontal regions may actively suppress activation of midline structures to augment performance. Similarly, a greater inverse correlation between activity in the default network and task-related activation was positively associated with
