The Architecture of Reward Value Coding in the Human Orbitofrontal Cortex

To ensure their survival, animals exhibit a number of reward-directed behaviors, such as foraging for food or searching for mates. This suggests that a core set of brain regions may be shared by many species to process different types of rewards. Conversely, many new brain areas have emerged over the course of evolution, suggesting potential specialization of specific brain regions in the processing of more recent rewards such as money. Here, using functional magnetic resonance imaging in humans, we identified the common and distinct brain systems processing the value of erotic stimuli and monetary gains. First, we provide evidence that a set of neural structures, including the ventral striatum, anterior insula, anterior cingulate cortex, and midbrain, encodes the subjective value of rewards regardless of their type, consistent with a general hedonic representation. More importantly, our results reveal reward-specific representations in the orbitofrontal cortex (OFC): whereas the anterior lateral OFC, a phylogenetically recent structure, processes monetary gains, the posterior lateral OFC, phylogenetically and ontogenetically older, processes more basic erotic stimuli. This dissociation between OFC representations of primary and secondary rewards parallels current views on lateral prefrontal cortex organization in cognitive control, suggesting an increasing trend in complexity along a postero-anterior axis according to more abstract representations. Together, our results support a modular view of reward value coding in the brain and propose that a unifying principle of postero-anterior organization can be applied to the OFC.