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Improving visual function through concomitant use of perceptual learning and brain stimulation : the case of macular degeneration

Abstract : Macular degeneration (MD) is a common visual disorder in the aging population characterized by a loss of central vision, reduced visual acuity contrast sensitivity, and increased crowding. This impairment strongly affects the quality of life and personal autonomy. There is currently no cure for AMD, available treatment options are only able to slow down the disease, and even palliative treatments are rare. After the emergence of the central scotoma, patients with MD develop one or more eccentric fixation areas - preferred retinal loci (PRLs) - that are used for fixation, reading, tracking, and other visual tasks that require finer ocular abilities. The final goal of the project was to investigate and to improve the residual visual abilities in the PRL. Four studies were conducted in total. Study 1 was conducted in MD patients to investigate whether after the emergence of the scotoma, the PRL acquire enhanced abilities in the processing of the visual information through spontaneous or use-dependent adaptive plasticity. Study 2 aimed to assess the effects of a single administration of transcranial random noise electrical stimulation (tRNS), a subtype of non-invasive transcranial electrical stimulation, on the spatial integration in the healthy visual cortex. Study 3 aimed to assess the between session effect of daily repeated tRNS coupled with perceptual training. The objective of study 4 was to translate the previous findings into a clinically applicable treatment approach by combining tRNS and perceptual training in adult patients with MD. Contrary to previous results, we found neither a phenomenon of spontaneous nor use-dependent cortical plasticity undergoing in the PRL before the training. We also found that the tRNS was able to modulate the visuospatial integration in the early visual processing, promoting plastic changes in the stimulated network. Its effects were not limited to the short-term modulation but also produced a boosting of the learning in a crowding task. The final experiment showed that a combination of tRNS and perceptual training could result in greater improvements and larger transfer to untrained visual tasks in adults with MD than training alone. Overall, our results indicate that tRNS of the visual cortex has potential application as an additional therapy to improve vision in adults with bilateral central blindness.
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Submitted on : Monday, November 16, 2020 - 7:13:07 PM
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Giulio Contemori. Improving visual function through concomitant use of perceptual learning and brain stimulation : the case of macular degeneration. Neurons and Cognition [q-bio.NC]. Université Paul Sabatier - Toulouse III; Università degli studi (Padoue, Italie), 2020. English. ⟨NNT : 2020TOU30054⟩. ⟨tel-03008570⟩

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