In addition to the SPE signals we observed in pIPS and latPFC, we also found evidence of RPE signals in the ventral striatum. This is consistent with many previous accounts (McClure et al., 2003; O’Doherty et al., 2003; Seymour et al., 2004). Our findings suggest that the two different types of learning signal are at least partly anatomically dissociable in the brain. Whereas the RPE is present predominantly in sub-cortical structures such as the striatum, appropriate to the rich input into this area from mid-brain dopaminergic neurons (Haber, 2003) known to broadcast this signal (Schultz, 1998; Schultz et al., 1997), the SPE was present instead in dorsal cortical areas, in the parietal and frontal lobes. The distinct neuroanatomical footprints of these signals could reflect the suggestion that they are being used to learn representations in two separate but interacting systems involved in behavioral control: a model-based (goal-directed) system that may involve a number of cortical areas in addition to parts of anterior medial striatum, and a model-free (habitual) system that may be depend predominantly on dopaminergic-striatal pathways (Balleine et al.,
