The NAcc is considered a key node in reward circuitry involved in assigning salience (Knutson and Cooper, 2005; McClure et al., 2004) and is hypothesized to be involved in vulnerability for addiction (Bjork et al., 2008b; Blum et al., 2000). Resting state studies of healthy subjects has shown positive functional connectivity between NAcc and cortical regions including the orbitofrontal, lateral temporal lobe and precuneus (Di Martino et al., 2008). Within-group PPI analysis in our control group revealed decreased task-related connectivity (Figure 2) with some of those same regions consistent with the responses of the brain’s default mode network (DMN) which decreases activity during attention-demanding tasks (Greicius and Menon, 2004; Mazoyer et al., 2001; Raichle et al., 2001). Areas positively correlated in resting state may have competing functions when task focus is necessary (Fox et al., 2005). Therefore task-related reductions in connectivity with DMN regions during reward processing may represent expected decoupling as focus shifts to process and react to incentive stimuli.
