Medial Prefrontal Cortex Represents the Object-Based Cognitive Map When Remembering an Egocentric Target Location.

A cognitive map, representing an environment around oneself, is necessary for spatial navigation. However, compared with its constituent elements such as individual landmarks, neural substrates of coherent spatial information, which consists in a relationship among the individual elements, remain largely unknown. The present study investigated how the brain codes map-like representations in a virtual environment specified by the relative positions of three objects. Representational similarity analysis revealed an object-based spatial representation in the hippocampus (HPC) when participants located themselves within the environment, while the medial prefrontal cortex (mPFC) represented it when they recollected a target object's location relative to their self-body. During recollection, task-dependent functional connectivity increased between the two areas implying exchange of self-location and target location signals between the HPC and mPFC. Together, the object-based cognitive map, whose coherent spatial information could be formed by objects, may be recruited in the HPC and mPFC for complementary functions during navigation, which may generalize to other aspects of cognition, such as navigating social interactions.