One of the key life-changing programs conducted at the Vision Institute is Cortical Vision. Retinal ganglion cell degeneration is one of the leading causes of blindness in the Western world. Ganglion cell degeneration occurs in a variety of pathological conditions, including ocular trauma, glaucoma, diabetic retinopathy, tumors, or optic neuropathies. Since retinal ganglion cells are the only conduits of visual information from the retina to higher visual centers, ganglion cell degeneration leaves the higher visual centers devoid of any visual input and, therefore, inevitably leads to complete blindness.
Our Cortical Vision program aims to restore visual perception by reintroducing visual information directly into higher visual centers, such as the thalamus or primary visual cortex of the brain, using prosthetics and optogenetic stimulation. Indeed, the successful translational steps towards ongoing clinical trials of prosthetic and optogenetic visual restoration following photoreceptor degeneration at the level of the retina have paved the way to transfer these technologies to restore visual activity by reactivating higher visual centers.
One lab doing this work is the Mayo Lab, also known as the Visual-Motor Neuroscience Laboratory. Since its inception April 1, 2020, the lab is committed to uncovering fundamental principles of brain processing to help improve and restore vision. This is done by studying the influence of eye movements on the activity of visual neurons in the cerebral cortex. “We hope to bridge the gap between well-controlled laboratory experiments and dynamic, natural primate vision,” Dr. J. Patrick Mayo said.
Another lab working in this area is the Laboratory of Visual Cognition, otherwise known as the Herman Lab, started March 1, 2021. “Human visual perception happens in the cerebral cortex, but it has become increasingly clear that visual functions also rely fundamentally on interactions between cortical areas and evolutionarily ancient “subcortical” brain structures,” said PI Dr. James Herman. “It is likely that subcortical-cortical interactions are vital for learning to use visual information in new ways, a process that likely occurs throughout the human lifespan. This hypothesis is particularly relevant to the Cortical Vision Project in which entirely new sources of visual information will be introduced to the brain – how will never-before experienced patterns of artificially induced activity in the visual cortex be interpreted? What will they mean? Learning to understand these new visual streams will be an important component of vision restoration programs. Work in my lab aims to understand how the activity of subcortical neuronal populations supports visual cognitive functions of all kinds, with a particular focus on the importance of learning.”
The newest lab is the Chen lab, run by Xing Chen, which develops high-channel-count, chronically implantable devices to record from and stimulate the brain. Their applications include the restoration of life-enhancing vision in the blind. Brain implants interface directly with visual regions in the brain, bypassing the retina and optic nerve to produce artificially generated percepts without input from the eye. Their neuroprostheses interface with large areas of the visual cortex, delivering tiny electrical currents to elicit the perception of dots of light (known as ‘phosphenes’). They deliver stimulation across multiple electrodes simultaneously, inducing percepts composed of multiple phosphenes, and causing their subjects to see movement and simple shapes such as letters.
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