Invited Session II: Visual Prosthetics: Artificial vision via high-channel-count visual cortical stimulation in...

Blindness affects 40 million people worldwide, and a neuroprosthesis may restore functional vision in the future. We developed a 1024-channel, chronically implantable prosthesis for the monkey visual cortex, using electrical stimulation to elicit percepts of dots of light ('phosphenes') across hundreds of electrodes. Phosphene locations matched the receptive fields of stimulated neurons, and V4 activity predicted phosphene detection during stimulation in V1. Next, we stimulated multiple electrodes simultaneously to generate percepts composed of multiple phosphenes. The monkeys could immediately recognize simple phosphene shapes, directions of motion, and letters. We developed techniques such as semi-automatic phosphene mapping and current thresholding, to expedite calibration of a prosthesis. Finally, we tested and validated several of our stimulation and calibration methods in blind human volunteers, demonstrating the potential of electrical stimulation to restore life-enhancing vision in the blind.