Patient research and studies with healthy individuals have indicated that the CNV might be related to the dopaminergic system (e.g., Amabile et al., 1986; Gerschlager et al., 1999; Linssen et al., 2011). Consequently, the observed interaction between task difficulty and reward in this component appears to be consistent with the results of the previous fMRI study of Krebs et al. (2012) showing a very similar interaction pattern in the dopaminergic midbrain with highest activation levels in respond to cues that predicted both reward and high difficulty. Of course, it should be noted that ERP measurements will not directly reflect activity in deep brain structures such as the dopaminergic midbrain (Cohen et al., 2011), but only through cortical consequences of its involvement. This possible link to the dopaminergic system raises another alternative, or possibly supplementary, interpretation for the current results. With higher levels of (reward) uncertainty, slower sustained activations of the dopaminergic system have been shown to increase (Fiorillo et al., 2003; Preuschoff et al., 2006). The current results related to late CNV amplitude are in line with this finding. The
