Abstract
Recent studies have shown that the spatial pattern of currents used on individual channels of cochlear implants can have a large effect on speech recognition and other measures of electrical-stimulus perception. This study is one of a series that seeks to understand the neural patterns of response underlying these effects. Guinea pigs were deafened in one ear by local perfusion of an antibiotic and implanted with an electrode array in the scala tympani. Psychophysical strength-duration functions (detection threshold versus electrical pulse duration) were obtained in guinea pigs trained using positive reinforcement, operant conditioning techniques. Single-unit data were obtained from inferior colliculus in the same animals, or in guinea pigs deafened and implanted in a similar manner. In these preparations, thresholds for neural responses were near the psychophysical thresholds at all phase durations, and the thresholds for the most sensitive neurons were several dB below the psychophysical detection thresholds. Thus, the paradoxical discrepancies between neural responsiveness and behavioral stimulus detection observed in previous comparisons made across animal models do not occur in this preparation. This seems to be a useful preparation for determining the spatiotemporal patterns of neural activity that underlie electrical-stimulus perception. [Work supported by NIH-NIDCD Grant No. DC00274.]
Published Version
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