An efficient multiplexing method for addressing large numbers of electrodes in a visual neuroprosthesis

Recent clinical trials using modified cochlear implants employ a small number of electrodes to stimulate surviving retinal neurons in blind patients and indicate that spatially-mapped phosphenes may indeed be elicited through these means. The next obvious step forward in the path toward achieving a useful visual prosthesis for the blind will be to increase the quantity of stimulation sites such that shapes, characters and rudimentary images may be conveyed. An important objective that must be obtained in the pursuit of this task is the ability to configure and deliver the stimulation with sufficient speed so as to avoid delays that are perceived by the patient as flicker within the visual scene. As the quantity of electrodes within the prosthesis increases, so too does the complexity of achieving this objective. This paper describes a means through which large numbers of electrode sites may be efficiently addressed in a neurostimulation circuit so as to increase the rate at which said circuit may be configured for the delivery of stimulation.