5 82 5. Towards biologically plausible phosphene simulation Figure S3: Example simulations of irregular phosphene percepts that can arise upon multi-electrode stimulation of three electrodes. By default, the simulator assumes independence between electrodes and their corresponding percepts. However, the code can be easily customized to simulate interactions between electrodes. In each of these examples, the base input is a stimulation vector describing the activation of three electrodes with a current of 100µA. The pulse width was set to 170µs, and the frequency was set to 300Hz. Before being sent to the simulator, the stimulation vector is processed by different custom interaction models. a) No interactions: the input is multiplied with the identity matrix before feeding to the simulator, resulting in phosphenes I, II and III. b) Co-activation: phosphenes I and II are activated by a weighted sum of the first two electrodes, simulating a ’leak’ between the electrodes, resulting in brighter phosphenes. c) Merging: a non-linear interaction model is used consisting of a two-layer fully-connected network with ReLU activation. When simultaneously activated, phosphenes I and II are replaced by a phosphene that falls in between the original locations. d) Arbitrary percept: similar to panel (c), the percepts of phosphenes I and II are replaced by a new percept when simultaneously activated. The new percept is an oblique line.
RkJQdWJsaXNoZXIy MTk4NDMw