extract the spontaneous BOLD modulations from a region such as the left somatomotor cortex and compute the correlation between this extracted signal and all other brain regions to obtain a map of the human somatomotor system (Biswal et al., 1995) (Figure 3). Anticorrelations between regions with apparent opposing functional properties have also been observed (Fox et al., 2005; Fransson, 2005). These spontaneous fluctuations predict the task-response properties of brain regions (De Luca et al., 2005; Vincent et al., 2006), identify subjects’ aptitude for different cognitive tasks (Hampson et al., 2006a; Seeley et al., 2007), facilitate refinement of neuro-anatomical models (Fox et al., 2006; Dosenbach et al., 2007), and account for trial-to-trial variability in behavior (Fox et al., 2007). Significant resting state fcMRI abnormalities have been identified across almost every major neurological and psychiatric disease (for reviews see (Greicius, 2008; Fox & Greicius, 2010; Zhang & Raichle, 2010)). As these resting state fcMRI abnormalities continue to be replicated, refined, and clarified, the next step will be translating this information into practical clinical interventions.
