Photochemical Brain-Machine Interface: Platform for Vision Prosthesis
Project Team: Dr. Joseph Kao, University of Maryland, Baltimore; University of Maryland, College Park
Project Duration: 36 Months
Project Objective: This project aims to develop a brain-machine interface (BMI) that can be the basis of a visual prosthesis. A BMI translates physical information (light intensity, sound pitch, etc.) into bioelectric signals that the brain can understand. The novelty of the proposed approach lies in using photochemistry to perform the translation. The BMI comprises two components: 1) A photochemical method for directly injecting image information into the cerebral cortex, ultimately in a blind human subject, so that the subject can perceive and navigate the external world, and 2) a device for implementing the photochemical method. The injection of information is accomplished by using spatio-temporally patterned and focused light pulses to photo-release “micro-packets” of neurotransmitter molecules that then activate specific groups of neurons in the visual cortex of the brain. Neurotransmitter photorelease is made possible by the use of photolabile, or “caged”, neurotransmitters. The device comprises a light-delivering array, consisting of individually-controllable microscopic point sources, that can be implanted onto or into the visual cortex to effect spatially and temporally controlled neurotransmitter release, flexible fiberoptic conduits that transport light to the sources in the array, an external light source (e.g., a laser) that supplies and modulates the light delivered to the array, a microfluidic pump for metered delivery of caged neurotransmitter to the cortex, as well as a mount for securing the implant relative to the brain/skull. The immediate application of this new technology is as a vision prosthesis for those who have lost their eyeballs and/or optic nerves. The major tasks of this project are:
1) Develop a compact and portable free-space optical activation platform (photoarray) for generating controllable light patterns.
2) Characterize and validate the photoarray performance in a non-tissue target.
3) Characterize and validate the photoarray performance in a visual cortex slice preparation.
In partnership with the US Army Medical Research & Materiel Command (USAMRMC), the Medical Technology Enterprise Consortium (MTEC) is pleased to announce the selectees in the second round of research project awards issued under its June 6, 2016 Brain Machine Interface Request for Project Proposals. The projects listed at the bottom of this page were selected by the USAMRMC to receive funding as indicated.
The project teams funded through these awards are focusing their activities on providing a prototype visual prosthesis for human testing within 5 years that (1) provides the ability to navigate for ambulation, identify faces and objects critical to daily life, and read large print, and (2) is economically feasible. The research project award recipients were selected from the Offerors who responded to MTEC’s Brain Machine Interface Request for Project Proposals (MTEC-16-02-Brain Machine Interface). This solicitation invited proposals focusing on the overarching goals toward the development of an appropriate brain-machine interface in key areas of prototype development that included:
- Stimulating visual pathways in either the a) the lateral geniculate nucleus (LGN) or b) primary visual cortex.
- Providing appropriate punctate stimuli with either a) electrical stimulation or b) optical stimulation for photolysis of caged excitatory neurotransmitters, photoswitches, or optogenetics (an optical stimulation delivery device is being sought, NOT the development of caged neurotransmitters, photoswitches or optogenetic tools).
- Providing density of stimulation for the equivalent of at least 20/40 in the central 2 of visual field.
- Stimulating neurons normally responsive to the peripheral field providing the equivalent of at least 70 of horizontal visual field for each eye.
- Prototypes must address specific anatomical challenges associated with implantation and communicating with the stimulation device.
- Prototypes must address biocompatibility (i.e., the prosthesis should ideally function for the lifetime of the patient).
- Demonstrating components of the device as a prototype in animal or appropriate in vitro models.
A Brain/Machine Interface for a Thalamic Visual Prosthesis
Project Team: Massachusetts General Hospital; Bionic Eye Technologies
Project Duration: 36 Months
Project Objective: A machine-to-brain interface is being developed to allow direct communication with the visual pathways in the brain to provide restoration of sight to blind individuals. This project concentrates on the most difficult part of the effort, the electrodes and stimulators required for delivering a video stream to neural tissue.
Insight: A Silicon Neural Probe Visual Prosthesis
Project Team: Scientific and Biomedical Microsystems, Cambridge Neuro, Oxford University, University of Pennsylvania
Project Duration: 36 Months
Project Objective: The aim of this project is to develop a prototype visual neuroprosthesis (or “artificial vision system”) and to validate its use in the primary visual cortex (V1) of non-human primates. In later phases of the project we will develop a system for use in chronic behavioral experiments in non-human primates, in support of translation to human clinical use. The work aims to address major technical hurdles related to the brain-machine interface (BMI) that is necessary for such a system to work successfully in humans, creating artificial vision for the blind, such as:
- Large-scale interfacing with deep brain targets while causing minimal tissue damage,
- Delivering tissue-layer specific stimulation patterns with complete spatiotemporal flexibility,
- Long-term, chronically stable, high resolution recording of neuronal activity to optimize stimulation parameters and monitor tissue health, and
- Spanning large volumes of brain tissue via an easily configurable, scalable modular architecture.
The novelty of this project is that it will demonstrate the first deployment of a BMI that has been engineered specifically from the ground up to optimize spatiotemporally, highly-resolved, long-term, chronic stimulation for a visual neuroprosthesis in the primary visual cortex. More generally, the scalable nature of our BMI, combined with the capability for long-term monitoring of neuronal signals, will facilitate the transfer of the approach to other areas of the brain and behaviors, such as restoring sensorimotor control and aiding functional recovery following traumatic brain injury and stroke.
Maximizing Vision Restoration Through Optimizing Brain Computer Interface Design
Project Team: Dr. Bradley Greger, Arizona State University; Second Sight Medical Products, Inc.
Project Duration: 36 Months
Project Objective: Visual perception can be induced through electrical stimulation of the nervous system driven by input from a small video camera – a vision prosthesis. Although recent clinical trials have demonstrated that limited vision can be restored in people who suffer vision loss due to Retinitis Pigmentosa, for many people with blindness a vision prosthesis that connects to the retina is not an option. Previous work has shown that stimulation of the primary visual cortex of the brain could induce simple patterns of visual perception and therefore may be able to serve as another approach to a vision prosthesis. The goal of our work is to validate and optimize such a cortical vision prosthesis. We will compare the level of vision restored using electrical stimulation via microelectrodes placed epicortically (on the surface of the visual cortex), or intracortically (within the visual cortex). The team also will determine the design parameters of a brain-computer interface that maximize the level of vision restoration provided by cortical microstimulation. The optimal microelectrode spacing and microstimulation parameters will be determined for both epicortical and intracortical microelectrode placement. The end goal of this project is to establish for a cortical vision prosthesis the design parameters useful for advancing into a human clinical study.