Full Scenes Produce More Activation than Close-Up Scenes and Scene-Diagnostic Objects in Parahippocampal and Retrosplenial Cortex: An fMRI Study

We used fMRI to directly compare activation in two cortical regions previously identified as relevant to real-world scene processing: retrosplenial cortex and a region of posterior parahippocampal cortex functionally defined as the parahippocampal place area (PPA). We compared activation in these regions to full views of scenes from a global perspective, close-up views of sub-regions from the same scene category, and single objects highly diagnostic of that scene category. Faces were included as a control condition. Activation in parahippocampal place area was greatest for full scene views that explicitly included the 3D spatial structure of the environment, with progressively less activation for close-up views of local scene regions containing diagnostic objects but less explicitly depicting 3D scene geometry, followed by single scene-diagnostic objects. Faces did not activate parahippocampal place area. In contrast, activation in retrosplenial cortex was greatest for full scene views, and did not differ among close-up views, diagnostic objects, and faces. The results showed that parahippocampal place area responds in a graded fashion as images become more completely scene-like and include more explicit 3D structure, whereas retrosplenial cortex responds in a step-wise manner to the presence of a complete scene. These results suggest scene processing areas are particularly sensitive to the 3D geometric structure that distinguishes scenes from other types of complex and meaningful visual stimuli.