Filling in the Visual Gaps: Shifting Cortical Activity using Current Steering

Cortical vision prostheses are being developed to restore sight in blind patients. Existing electrode arrays that electrically stimulate cortical tissue to artificially induce neural activity are difficult to position directly next to each other. Leaving space between implants creates gaps in the visual field where no visual percepts can be created. Here, we propose current steering as a solution to elicit a neural response between physical electrode locations. We assessed the centroid of neural activity produced by dual-electrode stimulation in the visual cortex of Sprague-Dawley rats. We determined that this centroid could be shifted between physical electrodes by altering the ratio of charge delivered to each electrode. This centroidal shift could enable better environmental perception for cortical implant patients by creating a complete visual field representation while maintaining safe array spacing.