Graeme Clark Collection

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Author: Shepherd, Robert × End date: 1995 × Start date: 1995 × Type: Conference Item × Subject: cochlear implant ×

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    Decrement in auditory nerve function following acute high rate stimulation in guinea pigs [Abstract]
    Tykocinski, M. ; Shepherd, R. K. ; Clark, Graeme M. ( 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.
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    Safety studies for a prototype Nucleus 22 channel implant at high stimulation rates [Abstract]
    Carter, P. M. ; Shepherd, R. K. ; Patrick, J. F. ( 1995)
    The safe stimulation of neural tissue requires that the stimulation does not produce any toxic electrochemical by-products and that the nerves are not damaged by the very act of responding to the stimulation. The Nucleus stimulator has been proven safe in several chronic animal studies using pulse rates of up to 500 pps and stimulus levels that produced sensations of moderate loudness, and subsequently in clinical use by more that 10,000 patients. Additional safety studies are necessary before considering the use of the Nucleus stimulator at higher rates. This paper describes in vitro investigations using such high rates while animal studies are currently under way to examine the effects of chronic, high rate stimulation.