Graeme Clark Collection
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ItemAcute effects of high-rate stimulation on auditory nerve function in guinea pigs( 1995)Cochlear implants have been shown to successfully provide profoundly deaf patients with auditory cues for speech discrimination. Furthermore, a number of safety studies using the Melbourne/Cochlear electrode array indicated that chronic electrical stimulation using charge-balanced biphasic current pulses and stimulus rates between 100 and 500 pulses per second (pps) do not result in additional spiral ganglion loss or general cochlear pathology.1-3 However, safe maximum levels for stimulus parameters (stimulus rate, charge per phase, charge density) have not yet been adequately defined.
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ItemPhysiological and histopathological effects of chronic monopolar high rate stimulation on the auditory nerve( 2000)Speech processing strategies based on high rate electrical stimulation have been associated with improvements in speech perception among cochlear implant users. The present study was designed to evaluate the electrophysiological and histopathological effects of long-term intracochlear monopolar stimulation at the maximum stimulus rate of the current Nucleus Cochlear implant system (14493 pulses/s) as part of our ongoing investigations of safety issues associated with cochlear implants
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ItemDecrement in auditory nerve function following acute high rate stimulation in guinea pigs [Abstract]( 1995)Cochlear implants have been shown to successfully provide profoundly deaf patients with auditory cues for speech discrimination. Psychophysical studies suggested that speech processing strategies based on stimulus rates of up to 1000 pulses per second (pps) may lead to an improvement in speech perception, due to a better representation of the rapid variations in the amplitude of speech. However, "neural fatigue" has been known to occur following brief periods of electrical stimulation at rates high enough to ensure that stimuli occur within the neurons relative refractory period, and has been shown to depend on stimulus duration and rate of the evoked neural activity. Prolonged electrical stimulation at these high stimulus rates could, therefore, have an adverse effect on the neurons metabolism and result in cellular energy depletion.