Invited Session II: Visual Prosthetics: Bidirectional communication with the human visual brain: Towards an advanced...

A long-held dream by scientists has been to directly transfer information to the visual cortex of blind individuals, to restore a rudimentary form of sight. However, in spite of all the progress in neuroelectronic interfaces, the biological and engineering problems for the success of cortical implants are much more complex than originally believed, and a clinical application has not yet been achieved. We will present our recent results regarding the implantation of intracortical microelectrodes in four blind volunteers (ClinicalTrials.gov identifier NCT02983370). Our findings demonstrate the safety and efficacy of chronic intracortical microstimulation via a large number of electrodes in humans, showing its high potential for restoring functional vision in the blind. The recorded neural activity and the stimulation parameters were stable over the whole experimental period, and multiple electrode stimulation evoked discriminable patterned perceptions that were retained over time. Moreover, there was a learning process that helped the subjects to recognize several simple and complex patterns. Additionally, our results show that we can accurately predict phosphene thresholds, brightness levels, and the number of perceived phosphenes from the recorded neural signals. These results highlight the potential for utilizing the neural activity of neighboring electrodes to accurately infer and control visual perceptions.