Exploring the Extent of Training-induced Visual Plasticity and the Potential for Use in Visual Rehabilitation
Author: Asmara Awada
Publisher:
Published: 2020
Total Pages:
ISBN-13:
DOWNLOAD EBOOK"In humans, vision represents the dominant source of sensory information about the external world, with more than half of the brain dedicated to the processing of visual information. Vision loss can thus be extremely devastating, with major impacts on quality of life. One of the most prevalent causes for visual deficit is stroke. Indeed, around 15 million people suffer a stroke every year with 30-50% of the cases associated with visual deficits. While two-thirds of stroke patients survive, the majority require months, or even years, of rehabilitation. However, to date, no clinically validated strategies exist to recover vision after stroke. However, the visual cortex remains highly plastic throughout the lifespan and can be retrained and reorganized to improve specific visual functions in a process known as visual perceptual learning. As a manifestation of pervasive plasticity occurring in the adult visual cortex, visual perceptual learning has a significant practical implication, providing high promise for use in visual rehabilitation. However, research in the field has identified a characteristic sensory specificity that limits its practical use. Recent advances have thus been devoted to exploring the neural basis of visual perceptual learning and to accordingly develop strategies that can overcome the sensory specificity. However, it remains unknown whether visual perceptual learning also exhibits effector specificity, imposing a larger limit on its practical use, and accordingly, whether non-specific recovery of visual function can be retrained in stroke patients. In Chapter 3 of this thesis, we show that while sensory specificity is prevalent in visual perceptual learning, effector specificity is not exhibited, providing increased promise for use in rehabilitation. In Chapter 4 of this thesis, we show that some visual function can be retrained in stroke patients through perceptual learning, but that a limit to recovery seems to exist. Overall, the findings of this thesis shed light on the nature of visual perceptual learning. Indeed, we provide evidence supporting the notion that perceptual learning represents a functional reorganization of visual information in parietal cortices but that the mechanism seems to be different in damaged cortices, limiting the kind of improvement that can be attained through training"--