October 2020
Volume 20, Issue 11
Open Access
Vision Sciences Society Annual Meeting Abstract  |   October 2020
Separate systems for transsaccadic comparisons of object orientation vs. identity in human cortex: An fMRI paradigm
Author Affiliations
  • Bianca Baltaretu
    Centre for Vision Research, York University, Toronto, ON, CA
    Vision, Science to Applications (VISTA) program, York University, Toronto, ON, CA
    Department of Biology, York University, Toronto, ON, CA;
  • J Crawford
    Centre for Vision Research, York University, Toronto, ON, CA
    Vision, Science to Applications (VISTA) program, York University, Toronto, ON, CA
    Department of Biology, York University, Toronto, ON, CA;
    Departments of Psychology, Kinesiology & Neuroscience Diploma Program, York University, Toronto, ON, CA;
Journal of Vision October 2020, Vol.20, 753. doi:https://doi.org/10.1167/jov.20.11.753
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      Bianca Baltaretu, J Crawford; Separate systems for transsaccadic comparisons of object orientation vs. identity in human cortex: An fMRI paradigm. Journal of Vision 2020;20(11):753. doi: https://doi.org/10.1167/jov.20.11.753.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Recently, Dunkley et al. (Cortex, 2016) showed that extrastriate cortex and right supramarginal gyrus (SMG) were modulated by transsaccadic changes in the orientation of a Gabor-like patch. However, this result did not generalize to other features: in a similar fMRI design, Baltaretu et al. (J Vis, 2016) found that transsaccadic changes in spatial frequency activated medial occipito-parietal and middle frontal gyrus (MFG). Based on this, we hypothesized that the fundamental difference between these results was the detection of transsaccadic changes in object orientation vs. identity. To test this, we used a double-dissociation fMRI task. Participants were asked to fixate on a small cross 15.4° left or right of centre, where an object was subsequently presented (rectangle, barrel-shaped object, or hourglass-shaped object), oriented at ±45° from vertical. After this, the fixation cross either remained in the same position (Fixate condition) or shifted to the other side (Saccade condition). Then, either the same object would appear with the opposite orientation (Orientation change condition) or one of the other two objects would appear at the same orientation (Identity change condition). Participants were required to indicate whether identity or orientation had changed using a button press. Preliminary analysis in seven participants, using an RFX GLM and a (Saccade Orientation > Identity) > (Fixation Orientation > Identity) contrast, showed that right SMG, inferior occipital gyrus, and left somatosensory and superior parietal lobe were significantly modulated by transsaccadic changes in object orientation. In contrast, right MFG, left primary motor cortex, and bilateral precuneus were significantly modulated by transsaccadic changes in object identity. These results support our hypothesis that separate anterior lateral (SMG) vs. posterior medial (precuneus) parietal nodes, respectively, are involved in the monitoring of object orientation versus identity across separate visual fixations.

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