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Julie Golomb, Nancy Kanwisher; Location information in category-selective areas: retinotopic or spatiotopic?. Journal of Vision 2010;10(7):950. doi: https://doi.org/10.1167/10.7.950.
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Challenging the classic view that the ventral and dorsal visual streams correspond to “what” and “where” pathways, recent studies have reported the existence of location information, independent of object category, in traditionally object-selective regions of ventral visual cortex (e.g., Schwarzlose et al, 2008, PNAS). Does the location information in these higher-order visual areas reflect pure retinotopic position, or absolute location independent of eye position? To find out, we functionally localized several regions in the ventral visual stream, including the lateral occipital complex (LOC), fusiform face area (FFA), parahippocampal place area (PPA), and extrastriate body area (EBA). We then used multivariate pattern analysis to measure category and location information within these areas during the main task, in which subjects viewed blocks of three different kinds of stimuli (faces, scenes, bodies) in four different locations. The four locations varied in both eye position and stimulus position, generating pairs of conditions in which the stimuli occupied different retinotopic (eye-relative) positions but the same spatiotopic (absolute screen) position, the same retinotopic position but different spatiotopic positions, the same in both retinotopic and spatiotopic position, or different in both. In each of the object-selective regions, we found both location-invariant category information and category-invariant location information, replicating Schwarzlose et al. Moreover, the location information was specific to retinotopic coordinates. That is, the multi-voxel pattern of fMRI response was more similar (i.e., more highly correlated) across conditions that shared the same retinotopic position than across conditions that shared the same spatiotopic position. Furthermore, there was no evidence of any spatiotopic location information in any of the regions examined. In early visual cortex (identified using retinotopic mapping), no category information was apparent, and location information was again exclusively retinotopic. These results suggest that even higher-order category-selective visual areas code stimuli according to a retinotopic coordinate frame.
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