Surface stimulation of the brain with a prototype array for a visual cortex prosthesis

We are developing a neural prosthesis to electrically stimulate the visual cortex to restore basic visual perceptions to blind patients. The effects on cortical excitation of different stimulus configurations using a prototype electrode array are presented. Cats underwent a bilateral craniotomy to expose the cortex. An array for brain stimulation was placed on the surface of the right hemisphere. Cortical stimulation was undertaken in a variety of configurations while measuring the evoked responses that propagated through transcallosal pathways, at a homologous region on the contralateral hemisphere. Cortical excitation elicited by stimulation with a particular paradigm could be assessed by measuring the spatial spread and amplitudes of evoked responses in the contralateral hemisphere. Results from this transcallosal model have allowed us to examine the spatial and amplitude effects of cortical stimulation with our prototype electrode array and will aid in developing a neuroprosthesis for blind patients.