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Pamela Knox, Sobana Wijeakumar, Anita Simmers, Uma Shahani; Is there a physiological marker for the effects of perceptual learning in amblyopia?. Journal of Vision 2012;12(9):1362. doi: 10.1167/12.9.1362.
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Introduction Recently, there has been a resurgence of interest in the visual training of amblyopia via perceptual learning (PL) techniques. The purpose of this study was to record the physiological consequences of PL in amblyopia by simultaneously recording cortical oxyhaemoglobin (HbO) concentration using functional near-infrared spectroscopy (fNIRS). If PL reflects changes in neural activity/recruitment, it is possible that the behavioural recovery in binocular function may be reflected in an alteration in HbO levels as a result of training. There is also the possibility that the recovery of binocular function may show a unique physiological marker. Methods 2 adult subjects with amblyopia and 2 age matched controls undertook a dichoptic perceptual learning task for 5 sessions (each lasting one hour) over the course of a week. The training paradigm involved a simple computer game, which correlated the visual inputs and required the subject to use both eyes to perform the task. Measurements of HbO concentrations over the primary visual cortex at locations O1 and O2 were made during the training tasks using fNIRS. Results A significant difference in the mean visual acuity of the amblyopic eye was demonstrated pre and post training along with measurable stereo function being established. HbO levels were found to be consistently lower in amblyopic subjects than in normal subjects and to increase over the period of training for both amblyopic and normal subjects but with a faster rate of change in normal participants. Conclusion The dichoptic based learning therapy employed in the current study appeared to be effective in improving monocular visual acuity in the amblyopic eye as well as improving stereo function. Changes in HbO levels recorded throughout the period of training were concurrent with clinical improvements in visual function suggesting that cortical plasticity can be modulated over very short time-scales.
Meeting abstract presented at VSS 2012
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