9624636 Kipke Cochlear implants are small wires inserted in the inner ear that can restore limited hearing to some profoundly deaf people. However, our understanding of the neurological mechanisms by which such implants work is far from complete. While we know that auditory areas of the cerebral cortex in adults continually change in response to the sounds that are listened to and to the onset of partial deafness, comparatively little is known about how these parts of the brain respond to long-term use of cochlear implants by hearing-impaired persons. Yet, this adaptation (or plasticity) of the cerebral cortex most likely plays a critical role in determining the ultimate effectiveness of the implants, and could provide a key to unlocking the world of sound for more hearing-disabled people. This project involves novel experiments and the development of new computer models to investigate the dynamics (extent and rate) of plasticity in auditory-related areas of the cerebral cortex in response to long-term electrical stimulation using cochlear implants. Array of hair-sized wire electrodes are implanted into the cerebral cortex of deafened animals that have been fitted with a cochlear implant. These electrodes allow monitoring of local neurological responses as the animals learn to "listen" via their cochlear implant. These responses are correlated with behavioral performance to gain insight into the brain's responses elicited by the implants and their functional significance. Concurrently developed computer models of the relevant brain areas and of the cochlear implant provide important analytical and visualization tools for understanding the complex mechanisms involved in cerebral cortex plasticity driven by the implants. This research is complemented by an education plan in which a graduate-level student internship is developed with a leading cochlear implant company. This internship extends beyond the conventional walls of academia by providing an opport unity for bioengineering students to gain substantive experience in a high- tech industrial setting. It is a mechanism for training students in science and engineering to contribute to advances in the U.S. medical device industry. This project provides critical new insight into how the brain adapts to long-term use of cochlear implants. A better understanding of cerebral cortex plasticity may lead to important new advances in cochlear implant design and patient training procedures. The project also provides important new opportunities for attracting talented bioengineering students who are interested in neural prostheses. Together these activities will ultimately, help increasingly larger numbers of hearing- impaired people regain the ability to enjoy the sounds of the world. ***
