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Grayson Roumeliotis, David Jones, Kathryn Murphy; Training improves orientation-in-noise thresholds in an animal model of amblyopia. Journal of Vision 2009;9(8):290. doi: https://doi.org/10.1167/9.8.290.
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© ARVO (1962-2015); The Authors (2016-present)
Binocular visual experience is necessary for the normal fine tuning of neural circuits in the visual cortex and the emergence of optimal signal-to-noise processing. A number of studies have suggested that the loss of visual acuity and contrast sensitivity after early monocular deprivation are a result of increased neural noise in the visual cortex. Here, our purpose is to determine the long-term effects of early monocular deprivation on neural signal-to-noise and whether intensive training with a visual signal-in-noise stimulus can ameliorate the visual deficits. We reared cats with either normal vision or a short period (2 weeks) of monocular deprivation early in the critical period. We then compared the impact of early training with a noise-free or noisy stimulus by measuring the developmental trajectory for grating acuity from one litter and orientation-in-noise thresholds from the other litter. The short period of monocular deprivation did not alter the developmental trajectory for either stimulus, or the adult grating acuity. Brief deprivation did, however, lead to poorer adult performance on the noise stimulus. Compared to normal cats, the deprived eye of cats with early training on noise required 10–15% more orientation signal to discriminate the target from noise. Surprisingly, even the non-deprived eye was affected, requiring 5–10% more orientation signal at threshold. Next, we measured orientation-in-noise thresholds for cats trained on grating acuity during development. Their thresholds were substantially worse, needing ∼ 30–50% more signal to make the discrimination; but after 2-3 weeks of intensive daily training, the thresholds began to improve. These findings reveal a prolonged development for the maturation of visual signal-in-noise processing with the deprived eye deficit not apparent until many weeks after the end of monocular deprivation. Finally, intensive training during development, or in young adults, can ameliorate much of the noise discrimination deficit caused by early visual deprivation.
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