OCULO-ENCEPHALOGRAPHIC PROCESSING

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This project will establish a new method of communication and environmental control by means of the visual evoked potential. Information is communicated by fixating one out of a number of flickering visual targets. The selected target is identified from the observer's evoked response which is derived from a pair of scalp electrodes. The feasibility has been proven in a preliminary study (64 targets average response time 2 seconds). The demonstrated performance is achieved by means of a novel, highly efficient technique of systems analysis. The research program is directed toward optimization of reliability and information transfer rate. It will include the study of electrode placement, target stimulus geometry (uniform fields, patterns, point sources), temporal stimulus characteristics (frame rate). The degradation of the scalp signal through muscle artifacts constitutes a major problem in practical applications. To eliminate these artifacts several techniques of nolinear filtering will be evaluated. Based on the results from these investigations, a portable system will be designed and built for evaluation of the concept outside the laboratory environment. The potential users of the communication and environmental control system are persons who are communicatively disabled through chronic conditions such as cerebral palsy, locked-in syndrome, or through progressive diseases such as amyotrophic lateral sclerosis, as well as persons in intensive care who are temporarity disabled. The Trace R and D Center for the Severely Communicatively Handicapped, at the University of Wisconsin, will evaluate the portable system with various subpopulations of users in comparative studies with other communication systems. The research program is aimed at the efficient extraction of the response contributions from several independent inputs to the visual system from the evoked response. The comparison of the extracted response contributions can not only be used for the purpose of communicaion but also for medical diagnostics. The prospect of such applications considerably widens the significance of the results from this project.