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Chuan Hou, Gabriela Acevedo Munares; Perceptual learning with attention tasks improves contrast sensitivity in V1 of human adults with amblyopia. Invest. Ophthalmol. Vis. Sci. 2021;62(8):160.
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© ARVO (1962-2015); The Authors (2016-present)
The neural correlates of perceptual learning in amblyopia remain unclear. The specificity of task orientation in behavioral studies is commonly interpreted as evidence that perceptual learning reflects plasticity in the primary visual cortex (V1). However, physiological evidence for this assumption is modest or controversial. To reveal neural correlates of perceptual learning, we measured contrast sensitivity in V1 of human adults with amblyopia using fMRI-informed EEG source imaging before and after perceptual learning.
A group of adults with amblyopia was trained using dichoptic attention tasks for about 2 visits/week for 2 months. The training task was to quickly search for and count the number of Targets presented in the trained eye while simultaneously being presented with Distractors in the untrained eye through a mirror stereoscope. We arranged 90% of trials with Targets in the amblyopic eye and only 10% of trials with Targets in the non-amblyopic fellow eye in each training session. We expected to improve attentional deployment considerably in the amblyopic eye. Contrast response function in each eye was measured by 128-channel swept parameter visual evoked potential (sVEP) before and after training. Contrast threshold was defined by using the regression to zero amplitude approach. V1 was defined by structure and fMRI in a separate session from EEG recordings. Contrast sensitivity (1/threshold) in V1 was compared in each participant pre and post training.
Contrast sensitivity in V1 improved for both the amblyopic and the fellow eye of adults with amblyopia after perceptual learning with attention tasks. The improvement was greater in the amblyopic eye than that in the fellow eye. We did not find significant difference in improvement between anisometropic and strabismic subgroups. Contrast sensitivity improvement in V1 indicates learning effect by enhancing attentional deployment in the amblyopic brain.
Perceptual learning with attention tasks improves contrast sensitivity in V1 of human adults with amblyopia. Our results suggest that top-down mechanisms play an important role in perceptual learning-induced plasticity in early visual cortex.
This is a 2021 ARVO Annual Meeting abstract.
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