Optimizing ultraflexible electrodes microstimulation parameters for inducing localized neuronal activation in mouse V1

Recent studies showed that flexible, ultra-thin, polyimide electrodes implanted in mouse V1 elicit chronically stable intracortical microstimulation (ICM) with low activation threshold and high biocompatibility, demonstrating their promising use as prosthetics for visual restoration. However, these works did not explore the full repertoire of parameters that can shape the ICM. Besides, to achieve precise spatial encoding of the visual field, it is necessary to identify the stimulation conditions that lead to localized neuronal activation around the stimulation site(s). We have developed a pipeline combining electrophysiological recordings and 2-photon imaging in mice to compare the excitatory neurons activation patterns elicited by different stimulation parameters (single vs double channel, monopolar vs bipolar, synchronous vs interleaved) and current amplitudes. In addition, we also test the effect of different distances between electrodes for double-channel conditions. This work has important implications for the development of next-generation visual prosthetics.