Central Visual Prosthesis with Interface at the Lateral Geniculate Nucleus
Abstract
The primary objective of this grant is to develop a novel type of visual prosthesis to restore vision to individuals who have suffered severe trauma to the eyes and optic nerves. This proposal addresses the Visual Prosthesis Pilot Study Award Focus Area defined as: "Studies to demonstrate the efficacy of novel cortical stimulation methodologies." Our proposed approach is an allowed exception to implantation at the visual cortex; our approach is to implant the electrodes at the lateral geniculate nucleus (LGN), as described below. Blindness is a significant and sometimes severe disability that robs an individual of independence and that increases the risk of inadvertent trauma, depression, obesity, and other health problems. Loss of vision due to damage to nerve tissue, like the retina or optic nerve, has not been treatable until very recently. Both biological and prosthetic approaches are being developed to restore vision to patients with neural blindness, and to date the more successful approach is the prosthetic strategy, in which a microelectronic device is placed into the eye to deliver electrical stimulation to nerve tissue that survives the blinding disease. This approach, which is often referred to as an ocular (or retinal) prosthesis, depends upon having a healthy connection between the eye and the brain (via the optic nerve). For our military personnel who suffer loss of the eyes or severe trauma to the eyes, or for patients with optic nerve disease like glaucoma, a retinal prosthetic is not applicable. Any prosthetic that is designed to restore vision to patients with severe ocular trauma or optic nerve disease must bypass the damage nerve tissue and deliver the electrical stimulation further along the visual pathway, somewhere within the brain. Several groups have been working to develop a visual cortical prosthesis, which will deliver electrical stimulation to the occipital cortex, where the visual part of the brain is positioned. This proposal seeks to develop a visual prosthesis that delivers electrical stimulation to the LGN, which is a special structure that lies midway between the eyes and the occipital cortex. Here, almost all nerve fibers from the eyes make synapses (i.e., connections), and the fibers emerging from the synapses then project to the occipital cortex. The LGN is very appealing for a visual prosthesis because of its anatomy that will make it easier to stimulate nerve cells but also because the surgery for this implantation is less invasive and easier than the surgery required to place stimulating electrode arrays over the visual part of the brain. Our team is the only one in the world that has been developing an LGN-based device. Part of our success is related to the close collaboration that we have had with the Department of Neurosurgery at the Massachusetts General Hospital/Harvard Medical School. This collaboration has demonstrated that electrical stimulation delivered to the LGN of a monkey was reliably used to make accurate eye movements. This proof-of-concept study supports the potential benefit of the LGN approach for humans. The success of our earlier monkey experiments was achieved with only four stimulating electrodes. There is a strong rationale for expecting that vision would be considerably better if more stimulation electrodes were available. Our Boston Retinal Implant Project (BRIP), which has been a collaboration between Harvard Medical School and the Massachusetts Institute of Technology since 1988, has produced a retinal prosthesis that has 256 individually controllable stimulating electrodes, which is more by far than any other neural prosthetic in the world. As such, the primary goal of this proposal is to leverage the considerable experience of our BRIP engineering team to create a novel LGN visual prosthetic with substantially more capability than was available at the time of the original experiments with monkeys. With the new device, we will
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1620015
Entities
People
- Joseph Rizzo
Organizations
- Massachusetts Eye and Ear Infirmary
- United States Army