脳の海馬傍回と鳥距下回の空間的視覚統合における異なる神経機構

To encode a cognitive map of an environment, a navigator must be able to integrate across perceptual views corresponding to the same place. This can be done in two ways. First, by integrating across the panorama of views obtainable at a single vantage point. Second, by integrating across views of a distal location containing a landmark that is visible from multiple vantage points. We tested the hypothesis that these two viewpoint integration processes are mediated by different neuroanatomical substrates. Male and female human participants were familiarized with a route through a virtual city. Storefronts along the route were pairwise associated in two ways: either by being on different buildings directly across the street from each other (panoramic association), or by being on different sides of the same building facing different streets (landmark association). Participants were then scanned with fMRI while they viewed the storefronts in isolation and performed a spatial memory task. Multivoxel pattern analyses revealed coding of panoramic associations in the retrosplenial complex (RSC) and several other regions within the medial and lateral parietal lobe including the medial place memory area (MPMA), lateral place memory area (LPMA), and the newly described superior parietal place memory area (SPPMA). In contrast, landmark associations were coded in the parahippocampal place area (PPA). These results demonstrate the existence of two neural mechanisms for integrating across views to represent places as either the observer's location (same panorama) or the observed location (same landmark).Significance statement An important component of spatial navigation is the ability to integrate across different views corresponding to the same place. Here we tested the idea that there are two such integration mechanisms in the human brain. Participants were familiarized with a virtual city and then scanned with fMRI while viewing storefronts from that city. Using multivariate pattern analysis, we find that the retrosplenial complex (RSC) and other parietal regions encode panoramas of views observed from specific locations, whereas the parahippocampal place area (PPA) encodes sets of views corresponding to specific landmarks. These results show that there are two anatomically separate mechanisms for integrating views into places, thus advancing our understanding of how the brain forms cognitive maps of spatial environments.