Spatial non-homogeneity of the antagonistic surround in motion perception

At high contrast, duration thresholds for motion direction discrimination deteriorate with increasing stimulus size. This counterintuitive result has been explained by the center-surround antagonism present in the neurons of visual area MT. Conversely, at very low contrast, direction discrimination...

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Bibliographic Details
Published in:Journal of vision (Charlottesville, Va.) Va.), 2011-02, Vol.11 (2), p.3-3
Main Authors: Serrano-Pedraza, Ignacio, Hogg, Ellen L, Read, Jenny C A
Format: Article
Language:English
Subjects:
Adolescent
Adult
Algorithms
Bayes Theorem
Contrast Sensitivity - physiology
Female
Form Perception - physiology
Humans
Male
Models, Neurological
Motion Perception - physiology
Photic Stimulation - methods
Psychophysics
Retina - physiology
Sensory Thresholds - physiology
Visual Cortex - physiology
Visual Pathways - physiology
Young Adult
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Summary:At high contrast, duration thresholds for motion direction discrimination deteriorate with increasing stimulus size. This counterintuitive result has been explained by the center-surround antagonism present in the neurons of visual area MT. Conversely, at very low contrast, direction discrimination improves with increasing size, a result that has been explained by spatial summation. In this investigation, we study the effects of stimulus shape and contrast on center-surround antagonism. Using adaptive Bayesian staircases, we measured duration thresholds of 5 subjects for vertically oriented Gabor patches of 1 cycle/deg with two types of oval Gaussian windows, one vertically elongated (Sx = 0.35, Sy = 2.5 deg) and other horizontally elongated (Sx = 2.5, Sy = 0.35 deg) moving rightward or leftward at a speed of 2 deg/s. We found that at high contrast (92%) duration thresholds were lower for vertically than horizontally elongated windows. However, at low contrast (2.8%), we found that duration thresholds were lower for horizontally than vertically elongated windows. These asymmetric results mirror the spatial non-homogeneity of the antagonistic surround found in MT neurons and suggest that the underlying center-surround antagonism is stronger along the direction of motion.
ISSN:1534-7362
1534-7362
DOI:10.1167/11.2.3