Functional Connectivity Between Human Hippocampus and Orbitofrontal Cortex Supports Inference-Based Decision Making

Internal representations of the relationships between entities or events, usually known as cognitive maps, enable individuals to make inferences from past experiences to guide decisions. Previous studies found both the hippocampus (HIP) and orbitofrontal cortex (OFC) are involved in this process. However, it is still unclear how the interaction between them responds to the inference-based decision. We recruited healthy adult subjects to perform an inference task during the functional magnetic resonance imaging (fMRI) scanning. Subjects were required to use their learned knowledge of hierarchical relationships to infer for novel decisions. We found that the HIP and OFC represented the cognitive map in social space. Beta-series correlation analysis revealed that inference-based decisions were accompanied by increased HIP-OFC connectivity. Moreover, the HIP-seeded correlation map included widespread regions in the visual areas, prefrontal cortex, medial temporal lobe, and temporoparietal cortex. The OFC-seeded correlation map contained visual areas, sensorimotor areas, prefrontal cortex, medial temporal lobe, temporoparietal cortex, insula, and putamen. These results suggested that the interactions between HIP and OFC may support inference-based decisions.