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Soojin Park, Marvin M. Chun; Different roles of the parahippocampal place area (PPA) and retrosplenial cortex (RSC) in scene perception. Journal of Vision 2007;7(9):767. doi: 10.1167/7.9.767.
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© ARVO (1962-2015); The Authors (2016-present)
One of the biggest challenges for human visual system is to create a seamless continuous world from multiple snapshots. Mediating this ability, there are at least two scene-sensitive regions of the brain, the parahippocampal place area (PPA) and retrosplenial cortex (RSC). Whereas the PPA is sensitive to changes in viewpoint of the same scene (Epstein, Graham & Downing, 2003), RSC may encode a more abstract scene-based representation independent of specific viewpoint (Bar & Aminoff, 2003; Epstein & Higgins, 2006; Park et al., 2006). To directly test this hypothesis, we presented different snapshot views from panoramic scenes. These views overlapped with each other by only 30%, so that they represented clearly different views, but appeared to come from the same panoramic scene. Using fMRI adaptation, we tested whether the PPA and RSC treated these panoramic views as the same or different. In the panoramic condition, three different views from a single panoramic scene were presented. In the identical condition, three identical views were presented. If the activity within the scene-selective ROI reflects an integrated scene representation, then we should observe attenuation in the panoramic condition. On the other hand, if the scene activity is specific to views, then we should observe no attenuation for panoramic repetition. We did not find any attenuation for panoramic repeats in the PPA, replicating a previous study (N=17). In contrast, the RSC showed significant attenuation for the panoramic condition. Both the PPA and RSC showed significant attenuation for the identical repetition. These results demonstrate that the PPA and RSC play different roles in scene perception: the PPA focuses on selective discrimination of different views while RSC focuses on the integration of scenes under the same visual context. Such integration may facilitate perception of a continuous world from multiple snapshots arising from eye and head movements.
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