Blindness disables millions of people across the world. In most cases, incurable blindness is caused by damage or dysfunction of the eye, retina, or optic nerve, but the visual cortex is undamaged and potentially functional. Electrical stimulation of visual cortex, even in blind patients, produces a percept of a distinct spots of light known as phosphenes. There has long been interest in developing a prosthetic device that employs direct activation of the intact visual cortex to restore vision to the blind. It has been speculated that phosphenes could serve as the building blocks for visual restoration in the blind; but unlike pixels in a video display, multiple phosphenes are not readily combined into a percept of a coherent form. We propose a novel stimulation paradigm, termed dynamic current steering, that can dramatically enhance the ability of visual cortical prosthetics (VCPs) to produce useful percepts of visual forms. Because there are imminent plans for clinical trials of several VCPs within the next few years, now is a currently particularly important time to develop improved methods for stimulation of visual cortex. To assess and refine dynamic current steering as a methodology for a VCP, we will measure percepts produced with this novel paradigm in pre-clinical testing in human epilepsy patients with implanted intracranial electrodes.
In Aim 1, we will test dynamic current steering as a novel method for producing percepts of visual forms.
In Aim 2, we will optimize the components of dynamic current steering to promote perception of coherent forms. Together, these aims will result in a novel paradigm for producing useful percepts of coherent visual forms by stimulation visual cortex that will be immediately translatable in forthcoming clinical trials of the next generation of VCPs.

Public Health Relevance

This project will test and refine dynamic current steering, a novel paradigm for electrical stimulation of sites in retinotopic visual cortex that will produce enhanced percepts of visual forms relevant to the future development and implementation of a visual cortical prosthetic. The results of this project will provide critical information that will help restore useful vision to the blind.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Flanders, Martha C
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Baylor College of Medicine
Schools of Medicine
United States
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Lázaro-Muñoz, Gabriel; Yoshor, Daniel; Beauchamp, Michael S et al. (2018) Continued access to investigational brain implants. Nat Rev Neurosci 19:317-318
Bosking, William H; Beauchamp, Michael S; Yoshor, Daniel (2017) Electrical Stimulation of Visual Cortex: Relevance for the Development of Visual Cortical Prosthetics. Annu Rev Vis Sci 3:141-166
Bosking, William H; Sun, Ping; Ozker, Muge et al. (2017) Saturation in Phosphene Size with Increasing Current Levels Delivered to Human Visual Cortex. J Neurosci 37:7188-7197