In vivo electrical stimulation of the optic nerve and hybrid computational model for neuroprosthetic applications

Blindness affects millions of people worldwide, dramatically decreasing their quality of life. Retinal dystrophies, such as age related macular degeneration and Retinitis Pigmentosa, which are leading causes of blindness in industrialized countries, currently have no cure. However, in both of these diseases, parts of the visual pathway remain intact and functional, and can elicit visual percepts when stimulated. Here, we are performing electrical stimulation of the optic nerve in rabbits that could lead to the development of a new neuroprosthetic device for sight restoration in blind patients. We opted to stimulate the optic nerve with a modified version of the SELINE electrode, a 12-channels flexible implant, shown to be biocompatible and able to selectively recruit different fascicles in the rat sciatic nerve. After optimization of the stimulation parameters, we demonstrated that the amplitude of the stimulating current and the number of stimulating pulses could modulate the intensity of the response in the visual cortex. We are now investigating more complex multi-channel stimulating protocols in order to show the possibility to selectively recruit different portions of the optic nerve. Lastly, we are currently developing a computational model of the optic nerve. It combines a 3D finite element method that allows to determine the voltage distribution generated in the optic nerve and a biophysical model of the optic nerve axons and their ionic channels dynamics that predicts which axonal population is recruited.