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Jeongho Park, Soojin Park; Coding of navigational distance in the visual scene-selective cortex. Journal of Vision 2018;18(10):739. doi: https://doi.org/10.1167/18.10.739.
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To successfully navigate, it is crucial to accurately detect local boundaries that impose limits to one's locomotion. In this study, we aim to directly examine the neural representation of navigational distance to a boundary in a scene. In Experiment1, we rendered artificial images that contain a transparent glass-wall, which presents a local boundary that limits one's navigation while keeping the visibility of a global boundary. The condition varied in 3 visible distance levels (Near, Middle, Far) and 2 local boundary levels (Glass-Wall, No-Glass-Wall). In Glass-Wall conditions, a transparent glass-wall was added to each environment, and critically, the navigational distance to the glass-wall was kept the same across all visible distance levels. We predicted that if there is a brain region representing the navigational distance, activation of such region will be distinguishable in No-Glass-Wall conditions but not in Glass-Wall conditions. During fMRI scans, participants (N=15) viewed the stimuli in a blocked design. We found a significant interaction between visible distance and local boundary in a scene-selective region, specifically Occipital Place Area (OPA). A step-wise increment of BOLD response was observed as the navigational distance increased in No-Glass-Wall conditions, but not when the navigational distance was kept the same in Glass-Wall conditions. Multivoxel pattern analysis also confirmed consistent results. These results suggest that OPA is sensitive to the changes of navigational distance in visual scenes. In Experiment 2, we tested a condition that contains a boundary that does not block one's navigation: curtains. Behavioral experiment showed that participants evaluate the navigational distance of curtain conditions to be similar to that of No-Glass-Wall conditions, suggesting the importance of functional constraint of a boundary (N=18). Preliminary fMRI results using the SVM classification replicate Experiment 1 findings. These results suggest that human scene-selective cortex acts as a perceptual source of critical information for the navigation.
Meeting abstract presented at VSS 2018
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