Large scale neuronal networks with characteristic low-frequency BOLD signal fluctuations such as the DMN are of interest in psychiatry for two reasons: one can study neuronal connectivity in psychiatric illness by examining the spatial integrity of these networks; and one can probe the contribution of specific networks to psychopathology by examining BOLD signal fluctuations in each network. Both are relevant to research in bipolar disorder and schizophrenia, two common and debilitating psychiatric conditions characterized by white matter abnormalities and disrupted signaling across large scale neuronal networks (Kubicki et al., 2007; Hasler et al., 2006; Mohamed et al., 1999; Morrison-Stewart et al., 1991). Indeed, recent studies have identified abnormalities in the DMN, especially in the anterior cingulate/medial PFC region, at rest or during task performance in chronic medicated outpatients with schizophrenia (Garrity et al., 2007; Bluhm et al., 2007; Liu et al., 2006; Liang et al., 2006), bipolar disorder (Calhoun et al., 2007), and major depressive disorder (Greicius et al., 2007). Since these regions subserve attentional modulation and assessment of emotional salience (Öngür and Price 2000), abnormalities within the DMN may
