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Michael-Paul Schallmo, Scott Murray; Identifying separate components of surround suppression during contrast perception in human subjects. Journal of Vision 2016;16(12):248. doi: 10.1167/16.12.248.
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© ARVO (1962-2015); The Authors (2016-present)
Surround suppression is a well-known phenomenon in which the response to a visual stimulus is diminished by other stimuli in the surrounding context. This effect is observed in neural responses in areas such as primary visual cortex, and also manifests in visual contrast perception. Studies in animal models have identified at least two separate mechanisms that may contribute to surround suppression: one that is monocular and resistant to contrast adaptation, and another that is binocular and strongly diminished by adaptation. The current study was designed to investigate whether these two mechanisms exist in humans and if they can be identified psychophysically using eye-of-origin and contrast adaptation manipulations. In addition, we examined the prediction that the monocular suppression component is broadly tuned for orientation, while suppression between eyes is narrowly tuned. Our results confirmed that when center and surrounding stimuli were presented dichoptically (in opposite eyes), suppression was orientation-tuned. Following adaptation in the surrounding region, no dichoptic suppression was observed, and monoptic suppression no longer showed orientation selectivity. These results are consistent with a model of surround suppression that depends on both low-level and higher-level components. This work provides a method to assess the separate contributions of these components during spatial context processing in human vision. Finally, we consider the possible neural substrates for these suppression components, including both cortical and pre-cortical mechanisms.
Meeting abstract presented at VSS 2016
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