We represent the locations of places (e.g., the coffee shop on 10th Street vs. the coffee shop on Peachtree Street) so that we can use them as landmarks to orient ourselves while navigating large-scale environments. While several neuroimaging studies have argued that the parahippocampal place area (PPA) represents such navigationally relevant information, evidence from other studies suggests otherwise, leaving this issue unresolved. Here we hypothesize that the PPA is, in fact, not well suited to recognize specific landmarks in the environment (e.g., the coffee shop on 10th Street), but rather is involved in recognizing the general category membership of places (e.g., a coffee shop, regardless of its location). Using fMRI multivoxel pattern analysis, we directly test this hypothesis. If the PPA represents landmark information, then it must be able to discriminate between 2 places of the same category, but in different locations. Instead, if the PPA represents general category information (as hypothesized here), then it will not represent the location of a particular place, but only the category of the place. As predicted, we found that the PPA represents 2 buildings from the same category, but in different locations, as more similar than 2 buildings from different categories, but in the same location. In contrast, another scene-selective region of cortex, the retrosplenial complex (RSC), showed the exact opposite pattern of results. Such a double dissociation suggests distinct neural systems involved in categorizing and navigating our environment, including the PPA and RSC, respectively.
Keywords: categorization; navigation; parrahippocampal place area (PPA); retrosplenial complex (RSC); scene processing.