Visual prosthesis simulator offers a glimpse into the future

Blindness affects approximately forty million people worldwide and is expected to become increasingly common in the coming years. Patients with a damaged visual system can be broadly divided into two groups: those in whom the damage is located in front of or in the photoreceptors of the retina; and those in whom the damage is further along in the visual system. Various retinal prostheses have been developed for the first group of patients in recent years and clinical tests are underway. The problems for the second group are more difficult to tackle.

A potential solution for these patients is to stimulate the cerebral cortex. By implanting electrodes in the brain’s visual cortex and stimulating the surrounding tissue with weak electrical currents, tiny points of light known as ‘phosphenes’ can be generated. This prosthesis converts camera input into electrical stimulation of the cerebral cortex. In doing so, it bypasses part of the affected visual system and thus allow some form of vision. You could compare it with a matrix sign along the highway, where individual lights form a combined image.

How we can ensure that such an implant can actually be used to navigate the street or read texts remains an important question. Maureen van der Grinten and Antonia Lozano, from Pieter Roelfsema’s group, along with colleagues from the Donder’s Institute, are members of a large European consortium. This consortium is working on a prosthesis that focuses on the visual cerebral cortex. Maureen van der Grinten emphasizes: 'At the moment there is a discrepancy between the amount of electrodes we can implant in people and the functionalities we would like to test. The hardware is simply not far enough yet. To bridge this gap, the process is often imitated through a simulation.'