December 2011
Volume 11, Issue 15
Free
OSA Fall Vision Meeting Abstract  |   December 2011
The Source of Overlay Masking in the Human Visual System
Author Affiliations
  • Damien Mannion
    Smith-Kettlewell Eye Research Institute & University of California, San Francisco, Neurology
  • Jeff Tsai
    Smith-Kettlewell Eye Research Institute & University of California, San Francisco, Neurology
  • Alex Wade
    Smith-Kettlewell Eye Research Institute & University of California, San Francisco, Neurology
Journal of Vision December 2011, Vol.11, 49. doi:10.1167/11.15.49
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      Damien Mannion, Jeff Tsai, Alex Wade; The Source of Overlay Masking in the Human Visual System. Journal of Vision 2011;11(15):49. doi: 10.1167/11.15.49.

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

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Abstract

The cortical response to an oriented pattern is influenced by the superimposition of a pattern of orthogonal orientation. This phenomenon, termed overlay masking (alternatively, cross-orientation suppression), manifests as a reduction in effective contrast that could be attributed to either primarily cortical or subcortical mechanisms. Here, we used source- imaged electroencephalography (EEG) to identify the source of overlay masking in the human visual system. We measured the response of neurons in primary visual cortex (V1) to an oriented test component of varying contrast, and examined how this response was altered by the superimposition of an orthogonal mask presented to the same eye (monoptic) or different eye (dichoptic). We found that a monoptic mask changed the effective contrast of the test component, consistent with overlay masking, while a dichoptic mask preserved the effective contrast of the test component and hence circumvented overlay masking. Given that dichoptic presentation precludes subcortical interactions between components, we identify subcortical mechanisms as the primary source of overlay masking in the human visual system.

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