A method for generating precise temporal patterns of retinal spiking using prosthetic devices

To restore meaningful vision to blind patients, retinal prosthetic devices should elicit spiking patterns in ganglion (output) cells that match the patterns normally generated by light. Here we have developed a method to generate high temporal precision spike trains that can mimic light-elicited patterns. Cell-attached patch clamp recordings were used to measure spiking responses from individual retinal ganglion cells in the flat mount rabbit retina. Biphasic electrical stimulus pulses were delivered epi-retinally by small-tipped platinum-iridium electrodes. Long duration electrical pulses (≥1 msec) elicited a single short-latency spike followed by a train of much longer latency spiking which was variable and depended on pulse amplitude levels. Short duration pulses (~0.1 msec) also elicited the single short-latency spike but no longer latency spikes. High frequency trains of short duration pulses also reliably elicited a single spike per pulse, suggesting that short duration pulse trains can be used to generate precise temporal patterns of spiking in ganglion cells. The short pulse stimulus paradigm allows us to mimic physiologically relevant light evoked responses, e.g., transient or sustained cells, as well as the spiking patterns that code for changes in intensity and contrast.