For the past 30 years, there has been extensive interest in developing a communication link between electronically controlled machines and the central nervous system for neuroprosthetics for spinal cord injury, blindness, prosthetic control and many other applications. However, all current applications of chronic neural interface technology are substantially hampered by lack of functional stability in the neural interface, possibly due to the mechanics of the stiff and tethered implants relative to the soft and dynamic brain. There are three dominant sources of mechanical mismatch the interconnects, the interconnect-electrode superstructure, and the electrodes themselves. Mechanical mismatch is a widely recognized shortcoming of the existing technology that this proposed program will largely overcome by creating a chronically implantable, thin, polymer based elastic thread-like interconnect technology that will integrate with the brain surface, and will access neurons of interest through flexible, threadlike electrodes with small but low impedance active sites. The objective of the proposed work is to develop a new cortical neural interface technology that physically and permanently integrates with the pia and cortex and that: 1) maintains long term physiological stability with specific target neurons; 2) are rugged and reliable for many decades; 3) can be readily atraumatically implanted; 3) utilizes advanced, non-fouling, low impedance/high charge capacity capacitive electrode material; and 4) could support economical rapid turn-around prototype runs of investigator generated designs. The feasibility of achieving this objective will be quantitatively assessed over the course of one year by an intense collaborative effort with Foster-Miller, Inc and InnerSea Technology, Inc. Physiological stability will be directly tested using a cortical barrel receptor (whisker) paradigm and automated action potential classification software. In addition, one of the most experienced quantitative histology laboratories in the world, Huntington Medical Research Institute, will provide independent, objective comparative histological analysis of the implanted tissues vs the extensively studied Iridium shaft electrode arrays that they have developed. Following the completion of this proposed Phase I work, the following will have been accomplished: 1) candidate tissue integrative electrode designs will have been identified and verified with mechanical testing (bench); 2) insertion techniques for these will have been developed and evaluated (bench and animals); 3) electrochemical and electrical parameters of the final electrode contacts will have been thoroughly documented (bench and animals); 4) preliminary testing of the physiological stability of the implant system relative to target neurons will have been completed and compared to similar testing in the contralateral cortex using Iridium arrays; and 5) initial objective quantitative assessment of the biocompatibility of the system will be complete. Phase II will begin limited commercialization for neuroprosthetics and other research, confirmation of biocompatibility and bioresistance, and testing of clinical applications in spinal cord injury. ? ? ?
