June 2004
Volume 4, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2004
Human cortical activations related to visual metacontrast masking
Author Affiliations
  • John-Dylan Haynes
    Institute of Cognitive Neuroscience, University College London, UK
Journal of Vision August 2004, Vol.4, 45. doi:10.1167/4.8.45
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      John-Dylan Haynes, Jon Driver, Geraint Rees; Human cortical activations related to visual metacontrast masking. Journal of Vision 2004;4(8):45. doi: 10.1167/4.8.45.

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

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Abstract

Metacontrast masking is a type of backward masking that occurs when a target is followed by a non-overlapping mask which shares a contour. We investigated responses of human visual cortex to novel metacontrast stimuli that maximised surface area of the target, while minimising mask size. Target-mask asynchrony and attention towards or away specific quadrants were manipulated orthogonally. Brain activations were characterised using functional MRI. Retinotopically mapped visual areas showed responses that varied in a qualitatively similar way to the psychophysically measured metacontrast masking function against SOA. While activations in V1 showed little attentional modulation, those in V2 and higher areas were strongly modulated by attention. Activations for both attended and unattended stimuli were related to the psychophysical masking function. Quantitatively, area V4 showed the closest match between fMRI response and the behavioural masking function against SOA. Strong and reliable fMRI responses that closely paralleled psychophysical performance were also identified in temporoparietal cortex, basal ganglia and prefrontal cortex. These results suggest that metacontrast masking modulates conscious perception and neural responses in humans not only in a retinotopically-specific manner within posterior visual cortex, but also in areas of prefrontal and parietal cortex.

Haynes, J.-D., Driver, J., Rees, G.(2004). Human cortical activations related to visual metacontrast masking [Abstract]. Journal of Vision, 4( 8): 45, 45a, http://journalofvision.org/4/8/45/, doi:10.1167/4.8.45. [CrossRef]
Footnotes
 This work was funded by the Wellcome Trust, and facilitated by the MRC Co-operative for the ‘Analysis of cognitive impairment and imaging of cognition’ at University College London.
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