Neural correlates of phosphene perception in blind individuals: A step toward a bidirectional cortical visual prosthesis

Blindness is one of the most impactful disabilities in human lives. Cortical prostheses could one day restore functional vision in some blind subjects, but their success will depend on integrating advanced technologies to realize the therapeutic benefits they promise. Most previous studies in humans used electrodes only for stimulation, which has made it challenging to precisely control the appearance of individual phosphenes. Herein, we implanted an intracortical microelectrode array of 100 electrodes in the visual cortex of two blind volunteers. We recorded the neural activity around the electrodes while performing electrical stimulation to induce visual perceptions. Besides showing how stimulation parameters influence perceptual thresholds, perceived brightness, and the minimum interval required to distinguish separate stimuli, our results indicate that subjective visual experience can be accurately predicted from the recorded neural activity. These results highlight the potential for using the neural activity of neighboring electrodes to accurately infer and control visual perceptions in cortical visual prostheses.