September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
Radial asymmetries in population receptive field size and cortical magnification factor in early visual cortex
Author Affiliations
  • Ben Harvey
    Experimental Psychology, Helmholtz Institute, Utrecht University
    Faculty of Psychology and Education Sciences, University of Coimbra
  • Jan Brascamp
    Department of Psychology, Michigan State University
  • Sónia Ferreira
    Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra
  • Miguel Castelo-Branco
    Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra
    Institute of Nuclear Sciences Applied to Health (ICNAS), Faculty of Medicine, University of Coimbra
  • Serge Dumoulin
    Experimental Psychology, Helmholtz Institute, Utrecht University
  • Maria Silva
    Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra
Journal of Vision August 2017, Vol.17, 587. doi:10.1167/17.10.587
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      Ben Harvey, Jan Brascamp, Sónia Ferreira, Miguel Castelo-Branco, Serge Dumoulin, Maria Silva; Radial asymmetries in population receptive field size and cortical magnification factor in early visual cortex. Journal of Vision 2017;17(10):587. doi: 10.1167/17.10.587.

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

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Abstract

Human visual cortex does not represent the whole visual field with the same detail. Changes in receptive field size, population receptive field (pRF) size and cortical magnification factor (CMF) with eccentricity are well established, and associated with changes in visual acuity with eccentricity. Visual acuity also changes across polar angle. However, it remains unclear how RF size, pRF size and CMF change across polar angle. Here, we examine differences in pRF size and CMF across polar angle in V1, V2 and V3 using pRF modeling of human fMRI data. In these visual field maps, we find smaller pRFs and larger CMFs in horizontal (left and right) than vertical (upper and lower) visual field quadrants. Differences increase with eccentricity, approximately in proportion to average pRF size and CMF. Similarly, we find larger CMFs in the lower than upper quadrant, and again differences increase with eccentricity. However, pRF size differences between lower and upper quadrants change direction with eccentricity. Finally, we find slightly smaller pRFs in the left than right quadrants of V2 and V3, though this difference is very small, and we find no differences in V1 and no differences in CMF. Moreover, differences in pRF size and CMF vary gradually with polar angle and are not limited to the meridians or visual field map discontinuities. Thus, the early human visual cortex has a radially asymmetric representation of the visual field. These asymmetries may underlie consistent reports of asymmetries in perceptual abilities.

Meeting abstract presented at VSS 2017

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