Iranian Journal of Biomedical Engineering 1 (2004) 3-14 * Corresponding author Address: Electronics Research Center, Electrical Engineering Department, AmirKabir University of Technology, Hafez St., Tehran, I.R.Iran Tel: +989123061754 Fax: +9821 8980227 E-mail: hsadjedi@yahoo.com ۱۰۳ A New Method for Selective Stimulation in Cochlear Implant Using Non-Simultaneous Multi Electrode Stimulation H. Sadjedi 1* , S. A. Motamedi 1 , S. M. P. Firoozabadi 2 1 Electrical Engineering Department, AmirKabir University of Technology 2 Medical Science Department, Tarbiat Modarres University Received 30 November 2003; received in revised form 14 July 2004; accepted 25 October 2004 ________________________________________________________________________________________________ Abstract Auditory nerve fibers stimulating using electrical current with implanted electrodes are the basis of cochlear implant system. Therefore, expansion of current spread in volume conductor will change the electrical potential in a larger region. This expansion causes larger region stimulation and decreases the accuracy and resolution of the stimulation in both the possibility of investigation of a particular region at Neural Response Telemetry (NRT) tests and also in hearing stimulation. Therefore, narrowing the width of stimulated region is the main goal in the selective stimulation. The conventional multi polar stimulation methods use lateral inhibitory electrode to form the spatial pattern of the electrical potential distribution for narrowing the stimulated region, but it needs to simultaneous stimulation of the electrodes, which is not available in implanted systems. In this paper, a new non-simultaneous multi-electrode stimulation method has been presented, which is based on applying the inhibitory pre-pulses by lateral electrodes. Inhibitory effect of the lateral electrodes pulses changes the initial conditions of the fibers and their thresholds. The results of simulations show that this method will solve the problem of simultaneous stimulation in conventional tri-polar stimulation methods and also is effective at controlling of stimulation area, comparing with tri-polar stimulation area, qualitatively and quantitatively. Keywords: Electrical stimulation; Multi electrode stimulation; Auditory nerve response; Cochlear implant; Selective stimulation DOI: 10.22041/ijbme.2004.13512 © Copyright 2005 ISBME, http://www.ijbme.org