September 2018
Volume 18, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2018
Prefrontal and category-selective ventro-temporal regions exhibit differential interactions between stimulus visibility and task
Author Affiliations
  • Lior Bugatus
    Department of Psychology, Stanford University, Stanford, CAStanford Neuroscience Institute, Stanford University, Stanford, CA
  • Kalanit Grill-Spector
    Department of Psychology, Stanford University, Stanford, CAStanford Neuroscience Institute, Stanford University, Stanford, CA
Journal of Vision September 2018, Vol.18, 389. doi:10.1167/18.10.389
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      Lior Bugatus, Kalanit Grill-Spector; Prefrontal and category-selective ventro-temporal regions exhibit differential interactions between stimulus visibility and task. Journal of Vision 2018;18(10):389. doi: 10.1167/18.10.389.

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Abstract

How do task relevance and stimulus visibility affect responses to visual categories in human ventral temporal cortex (VTC) and ventro-lateral prefrontal cortex (VLPFC)? We addressed this question by conducting 2 fMRI studies in 5 participants who viewed stimuli from three visual categories (faces, cars, and houses), at three visibility levels (low: 20% opacity, mid: 25% opacity, and high: 50% opacity), while performing either an exemplar or a fixation task. In the exemplar task, subjects were cued to detect a particular exemplar (occurring 0-4 times within a block of 12 images from a category). In the fixation task, subjects viewed the same stimuli, but were cued to detect a fixation color (occurring 0-4 times in a block). Subjects also participated in a whole brain anatomical scan as well as a localizer used to define regions of interest (ROIs) selective to faces and places. Results reveal that face and place-selective ROIs in VTC exhibited an interaction between task and visibility: In the exemplar task, response amplitudes were similar across the three visibility levels, but during the fixation task responses increased with visibility level, particularly for the preferred stimulus. These data suggest that in VTC, top-down attention to an exemplar can override the effects of bottom-up stimulus visibility. In contrast, in the VLPFC, inferior frontal junction (IFJ) exhibited an opposite pattern of response: In the exemplar task, responses to visual categories in IFJ decreased with increased visibility, but during the fixation task, responses were similar across visibility levels and were indistinguishable from baseline. These data suggest that IFJ responses are modulated by both task relevancy and difficulty. Together these data suggest that top-down influences from prefrontal regions onto category-selective ventral-temporal regions enhance the latter's response during low visibility conditions only when these are task relevant.

Meeting abstract presented at VSS 2018

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