During the evaluation of monetary loss and gain, the common features of the CSD topography observed across groups were the sources (positivities) in left-frontal, right-frontal and mid-frontal regions (Fig. 6). Our finding that prominent CSD sources were located at the frontal regions corroborates existing evidence that cognitive tasks requiring evaluations of reward outcomes recruit the frontal lobes (Wallis and Miller, 2003; Glascher et al., 2010; Rangel and Hare, 2010). There is also a strong literature support for the major involvement of frontal lobes (connecting a network of other subcortical structures) during reward processing and decision making (Haber and Knutson, 2010; Rushworth et al., 2011; Economides et al., 2014; Forbes et al., 2014). Specifically, medial prefrontal cortex (mPFC) involving ACC has been shown to be involved in the processing of the reward values of the reinforcers (O’Doherty et al., 2001; Shidara and Richmond, 2002; Knutson et al., 2003; Rogers et al., 2004; Knutson et al., 2005; Shidara et al., 2005; Taylor et al., 2006; Sallet et al., 2007; Fujiwara et al., 2009; Xue et al., 2009; Economides et al., 2014).
