FMRI INVESTIGATIONS OF THE PARAHIPPOCAMPAL PLACE AREA

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All navigating organisms must answer the fundamental question, where am I now? FMRI research in my lab over the last 8 months has identified a region of cortex we call the parahippocampal place area (PPA), which appears to play a central role in solving that problem. We have functionally localized the PPA in 28 out of 30 subjects tested and have shown that the PPA responds in a highly selective fashion to visual stimuli depicting places, responding robustly when subjects view photographs of indoor and outdoor scenes, yet only very weakly to photographs of common objects and faces. The goal of the proposed research is to specify the precise function of the PPA associated neural structures (e.g., the hippocampus, perirhinal and entohinal cortex, and parietal regions) in place perception, navigation, and spatial cognition. The experiments in Part I lay the groundwork for future studies by characterizing the anatomical and functional properties of the PPA and associated structures in detail. The experiments in Part II are designed to precisely characterize the kinds of stimuli that drive the PPA. Having clearly defined the categories of stimuli that activate the PPA, Part III will determine the nature of the processing the PPA and associated neural structures carry out on those stimuli. Specifically, these experiments test the involvement of the PPA and other regions in I) the perceptual analysis of the stimulus (the Perception Hypothesis), ii) the comparing of that perceptual information to stored representations of the appearances of places (the Recognition Hypothesis), iii) the encoding of theat perceptual information into memory (the Memory Encoding Hypothesis), and/or iv) determining how to get from the current location to some other known location in the cognitive map, i.e. route planning (the Route-Planning Hypothesis)