In a visual prosthesis or other neural stimulator it is advantageous to provide non-overlapping pulses in order to provide independent control of brightness from different electrodes. Non-overlapping pulses on geographically close electrodes avoid electric-field interaction which leads to brightness summation or changes in the shape and area of percepts. It is advantageous to apply pulses to nearby electrodes in a way that the currents do not overlap in time at all. ‘Nearby’ is defined as within a few millimeters of each other. The same parameters that provide independent control of brightness also produce spatial patterns that the subjects' report as being similar to the sum of individual electrode phosphenes. Simultaneous stimulation of multiple electrodes can sometimes produce physical sensation or discomfort in the eye. Time-shifting the pulses cab also be used to reduce the physical sensations felt by the patient.
Visual prosthesis for control of spatiotemporal interactions