Publications using the IZ2M & IZ2MH

Neural implants that deliver multi-site electrical stimulation to the nervous systems are no longer the last resort but routine treatment options for various neurological disorders. Multi-site electrical stimulation is also widely used to study nervous system function and neural circuit transformations. These technologies increasingly demand dynamic electrical stimulation and closed-loop feedback control for real-time assessment of neural function, which is technically challenging since stimulus-evoked artifacts overwhelm the small neural signals of interest. We report a novel and versatile artifact removal method that can be applied in a variety of settings, from single- to multi-site stimulation and recording and for current waveforms of arbitrary shape and size. The method capitalizes on linear electrical coupling between stimulating currents and recording artifacts, which allows us to estimate a multi-channel linear Wiener filter to predict and subsequently remove artifacts via subtraction. We confirm and verify the linearity assumption and demonstrate feasibility in a variety of recording modalities, including in vitro sciatic nerve stimulation, bilateral cochlear implant stimulation, and multi-channel stimulation and recording between the auditory midbrain and cortex. We demonstrate a vast enhancement in the recording quality with a typical artifact reduction of 25-40 dB. The method is efficient and can be scaled to arbitrary number of stimulus and recording sites, making it ideal for applications in large-scale arrays, closed-loop implants, and high-resolution multi-channel brain-machine interfaces.

Retinal prostheses can restore a functional form of vision in patients affected by dystrophies of the outer retinal layer. Beyond clinical utility, prostheses for the stimulation of the optic nerve, the visual thalamus or the visual cortex could also serve as tools for studying the visual system. Optic-nerve stimulation is particularly promising because it directly activates nerve fibres, takes advantage of the high-level information processing occurring downstream in the visual pathway, does not require optical transparency and could be effective in cases of eye trauma. Here we show, in anaesthetized rabbits and with support from numerical modelling, that an intraneural electrode array with high mechanical stability placed in the intracranial segment of the optic nerve induces, on electrical stimulation, selective activation patterns in the visual cortex. These patterns are measured as electrically evoked cortical potentials via an ECoG array placed in the contralateral cortex. The intraneural electrode array should enable further investigations of the effects of electrical stimulation in the visual system and could be further developed as a visual prosthesis for blind patients.