This is a revised application for a proposed Bioengineering Partnership to research strategies for an intracortical visual prosthesis. During the past 30 years, the NIH has funded studies that provided significant advances in electrode technology and establishment of criteria for safe stimulation of the visual cortex. However, the integration of electrodes into reliable, interconnected multichannel arrays, implantable multichannel stimulators, and the fundamental visual science studies to determine the functional usefulness of an intracortical prosthesis are lacking. For this reason, previous studies are an insufficient basis for considering whether proceeding to chronic human implantation is warranted. The overall objectives of the proposed program are to advance the technology sufficiently to provide a reasonable expectation of reliability and safety for implantable hardware, develop an animal model to perform crucial psychophysical and electrical stimulation studies, and address patient-volunteer psychological and ethical issues of a future chronically-implanted intracortical visual prosthesis.
The Specific Aims are: 1. Develop a primate animal model for testing the sensory responses to large numbers of parallel intracortical stimulation electrodes. 2. Extend earlier human work on point-phosphene perception to a more general approach that exploits other V1 tuning properties, such as orientation selectivity, to create a richer visual feature set. This will be done by psychophysical testing in the animal model. 3. Demonstrate safety, efficacy, and electrochemical stability of our proposed intracortical electrode arrays using a combination of in vitro and in vivo testing. 4. Determine the optimal physical configuration for, and design a high-reliability implantable inductively-powered stimulator, interfaced to an external computer controller. 5. Develop safe implantation methods, including pre- and post-operative imaging techniques, to optimize and minimize the duration of implant surgical procedures. 6. Establish criteria for proceeding to a future human implantation using a thorough multi-faceted examination of ethical and psychological issues.
