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Satoru Suzuki, Marcia Grabowecky; Long-term speeding of alternations in binocular rivalry: Potential mediation by primary visual cortex.. Journal of Vision 2004;4(8):62. doi: 10.1167/4.8.62.
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© ARVO (1962-2015); The Authors (2016-present)
In binocular rivalry (BR), a distinct image is presented to each eye and perception tends to spontaneously alternate (every 0.5–3 sec or so) between the two images. BR has been used extensively to understand how inhibitory neural interactions at “low-level” (interocular) and “high-level” (global-pattern-based) processing contribute to spontaneous alternations of visual awareness. BR also provides a unique opportunity to study how the adult visual system might adapt to a novel environment in which the two eyes are repeatedly co-activated by an incoherent pair of images. This question is interesting as it is known that coherent activation of the two eyes is crucial for the development of V1 binocular cells. We thus examined effects of long-term exposure to simple BR stimuli, consisting of vertical, horizontal, and oblique bars (e.g., a dark “+”in the left eye and a light “×” in the right eye). We replicated a finding that the rate of perceptual alternations gradually slowed as the observer continuously viewed a BR display (probably due to contrast adaptation). Significantly, perceptual alternations SPEEDED as the observer repeatedly experienced the same BR display over weeks of exposure. We assessed the locus of this long-term plasticity by testing the transfer of the speeding effect. The effect was highly specific to orientation (substantially reduced when images were rotated by 23 ) and position (eliminated when images were shifted by 1 visual angle), suggesting an early locus of plasticity. Furthermore, the plasticity must involve monocular neurons because the speeding effect substantially reduced when the assignment of the stimuli to the left and right eyes was reversed. This eye and feature contingent speeding of BR demonstrates the retained plasticity of the adult binocular system, suggesting that extensive experience with identical rivaling configurations increases associations between co-activated monocular cells.
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