Restoration of visual function via perceptual learning that targets specific brain areas

 

Following stroke or traumatic brain injury, many patients exhibit cortical visual impairment (CVI), usually in the form of a large blind spot in the visual field opposite the injury. In high-income countries, CVI is now the leading cause of vision loss in children, and pediatric CVI is ten times more prevalent in low-income countries. Overall, the population of CVI patients numbers approximately 20 million worldwide, the vast majority of whom receive no treatment whatsoever.

CVI results specifically from damage to the primary visual cortex (area V1) or the structures leading to it, but most patients actually have access to visual input via a pathway from the eye to the extrastriate cortex, a collection of brain areas that encode complex visual stimuli. This pathway bypasses area V1, and it often supports a kind of subconscious vision known as “blindsight”. Although there is some evidence that this pathway can be strengthened with appropriate training protocols, there has been very little effort to design appropriate therapies.

The aim of this project is to develop novel therapies for treating CVI, based on recent advances in our understanding of brain plasticity. More specifically, the research team will examine how the brain regions responsible for visual perception change when subjects are trained to identify particular visual stimuli. The project will also identify brain regions responsible for maintaining visual signals in memory across eye movements and develop training procedures that maximize the effectiveness of this integration. These findings will be used to design novel training protocols for CVI patients. The benefits will likely be greatest for pediatric patients, given their greater potential for plasticity. The project will provide a strong research environment and capacity building and exchange opportunities for graduate students, clinicians, and researchers based in Nepal.

The project is led in Canada by McGill University in collaboration with the Hebrew University of Jerusalem in Israel and the Tilganga Institute of Ophthalmology in Nepal.

This project was selected for funding through the fourth research competition of the Joint Canada-Israel Health Research Program. This initiative is a partnership between IDRC, the Canadian Institutes of Health Research, the Israel Science Foundation, and the Azrieli Foundation.