August 2016
Volume 16, Issue 12
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2016
Mechanisms for encoding navigational boundaries in the mammalian brain
Author Affiliations
  • Joshua B Julian
    Department of Psychology, University of Pennsylvania
  • Alex T Keinath
    Department of Psychology, University of Pennsylvania
  • Jack Ryan
    Department of Psychology, University of Pennsylvania
  • Roy H Hamilton
    Department of Neurology, University of Pennsylvania
  • Isabel A Muzzio
    Department of Biology, University of Texas: San Antonio
  • Russell A Epstein
    Department of Psychology, University of Pennsylvania
Journal of Vision September 2016, Vol.16, 8. doi:10.1167/16.12.8
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      Joshua B Julian, Alex T Keinath, Jack Ryan, Roy H Hamilton, Isabel A Muzzio, Russell A Epstein; Mechanisms for encoding navigational boundaries in the mammalian brain. Journal of Vision 2016;16(12):8. doi: 10.1167/16.12.8.

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      © 2017 Association for Research in Vision and Ophthalmology.

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Abstract

Thirty years of research suggests that environmental boundaries exert powerful control over navigational behavior, often to the exclusion of other navigationally-relevant cues, such as objects or visual surface textures. Here we present findings from experiments in mice and humans demonstrating the existence of specialized mechanisms for processing boundaries during navigation. In the first study, we examined the navigational behavior of disoriented mice trained to locate rewards in two chambers with geometrically identical boundaries, distinguishable based on the visual textures along one wall. We observed that although visual textures were used to identify the chambers, those very same cues were not used to disambiguate facing directions within a chamber. Rather, recovery of facing directions relied exclusively on boundary geometry. These results provide evidence for dissociable processes for representing boundaries and other visual cues. In a second line of work, we tested whether the human visual system contains neural regions specialized for processing of boundaries. Specifically, we tested the prediction that the Occipital Place Area (OPA) might play a critical role in boundary-based navigation, by extracting boundary information from visual scenes. To do so, we used transcranial magnetic stimulation (TMS) to interrupt processing in the OPA during a navigation task that required participants to learn object locations relative to boundaries and non-boundary cues. We found that TMS of the OPA impaired learning of locations relative to boundaries, but not relative to landmark objects or large-scale visual textures. Taken together, these results provide evidence for dedicated neural circuitry for representing boundary information.

Meeting abstract presented at VSS 2016

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