Anchoring the neural compass: Coding of local spatial reference frames in human medial parietal lobe

The neural systems that code for location and facing direction during spatial navigation have been extensively investigated; however, the mechanisms by which these quantities are referenced to external features of the world are not well understood. To address this issue, we examined behavioral priming and fMRI activity patterns while human subjects re-instantiated spatial views from a recently learned virtual environment. Behavioral results indicated that imagined location and facing direction were represented during this task, and multi-voxel pattern analyses indicated the retrosplenial complex (RSC) was the anatomical locus of these spatial codes. Critically, in both cases, location and direction were defined based on fixed elements of the local environment and generalized across geometrically-similar local environments. These results suggest that RSC anchors internal spatial representations to local topographical features, thus allowing us to stay oriented while we navigate and to retrieve from memory the experience of being in a particular place.