Abstract
Epstein & Kanwisher (1998) identified a region of the parahippocampal gyrus which responded more strongly to scenes depicting places than to other types of visual stimuli (such as faces and places). The activity of this area, termed the parahippocampal place area (PPA), was not affected by the subject's familiarity with the location, but was reduced by subsequent presentations of the same scene (Epstein et al., 1999), and showed responsiveness whenever a stimulus conveyed information about the spatial layout. We sought to understand whether the PPA is modulated by the degree of depth present in the scene and whether the scene is enclosed (indoors) or outdoors. In addition, we also characterized the differential cortical response to these scene types in the surrounding tissue of the ventral visual pathway. Subjects passively viewed 1 sec presentations of pictures of individual objects, indoor scenes, outdoor scenes of near focus, or outdoor scenes with far focus (e.g. vistas) in separate blocks while fMRI activity was recorded. We identified a set of voxels in the parahippocampal gyrus bilaterally which responded more to scenes (regardless of type) than to objects. Within these voxels, we found that indoor scenes produced greater activity than outdoor scenes with close focus, which in turn produced greater activity than outdoor scenes with far focus. However, this pattern was generally reversed deep in the temporal poles, as activity was greater for outdoor scenes than for indoor scenes, and that near focus scenes produced less activity in the temporal poles than vistas. We conclude that while there may be one region which responds greater than objects for all scene types, its activity is modulated by scene type, and some scenes produce significant amounts of activity at more anterior and inferior locations.
Supported by Human Frontiers Science Program Organization RG0035/2000B, MURI ARO DAAG55-98-1-0293, James McDonnell Foundation 99-53.