Abstract
Complex real-world scenes can either be identified at the basic level (“a store”) or as specific places with specific locations in the world (“the Penn Bookstore at 36th and Walnut St.”). We used fMRI to test whether these two recognition tasks engage the same or different neural systems. In each trial of Exp. 1, subjects saw a verbal label followed by a briefly presented and masked photograph and reported whether the label matched the photograph. In location identification trials, stimuli were names and photographs of familiar locations around the Penn campus, while in category identification trials, stimuli were names and photographs of easily categorizable unfamiliar scenes (“kitchen”, “parking lot”). Scene-responsive voxels in the parahippocampal place area (PPA) and retrosplenial cortex (RSC) responded much more strongly during location identification than during category identification. Exp. 2 was a control experiment that replicated these results in a new set of subjects and demonstrated that they could not be accounted for by stimulus differences. Exp. 3 and 4 demonstrated different roles for the PPA and RSC during location identification, with the PPA supporting a representation of the local scene that can be activated by either visual or verbal stimuli and the RSC supporting processes that may facilitate the placement of the local scene within a larger spatial framework. These results are consistent with the claim that PPA and RSC are preferentially involved in localization rather than categorization of scenes and point to the existence of distinct neural systems involved in these two tasks.
This research was supported by a grant from the Whitehall Foundation.