Bierer Julie Arenberg
Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd Street, Box 354875, Seattle, Washington 98105-6246, USA.
J Acoust Soc Am. 2007 Mar;121(3):1642-53. doi: 10.1121/1.2436712.
The efficacy of cochlear implants is limited by spatial and temporal interactions among channels. This study explores the spatially restricted tripolar electrode configuration and compares it to bipolar and monopolar stimulation. Measures of threshold and channel interaction were obtained from nine subjects implanted with the Clarion HiFocus-I electrode array. Stimuli were biphasic pulses delivered at 1020 pulses/s. Threshold increased from monopolar to bipolar to tripolar stimulation and was most variable across channels with the tripolar configuration. Channel interaction, quantified by the shift in threshold between single- and two-channel stimulation, occurred for all three configurations but was largest for the monopolar and simultaneous conditions. The threshold shifts with simultaneous tripolar stimulation were slightly smaller than with bipolar and were not as strongly affected by the timing of the two channel stimulation as was monopolar. The subjects' performances on clinical speech tests were correlated with channel-to-channel variability in tripolar threshold, such that greater variability was related to poorer performance. The data suggest that tripolar channels with high thresholds may reveal cochlear regions of low neuron survival or poor electrode placement.
人工耳蜗的功效受到各通道间空间和时间相互作用的限制。本研究探讨了空间受限的三极电极配置，并将其与双极和单极刺激进行比较。阈值和通道相互作用的测量结果来自9名植入Clarion HiFocus-I电极阵列的受试者。刺激为以1020脉冲/秒传递的双相脉冲。阈值从单极刺激到双极刺激再到三极刺激逐渐升高，且在三极配置下各通道间变化最大。通道相互作用通过单通道和双通道刺激之间阈值的变化来量化，三种配置均出现通道相互作用，但在单极和同时刺激条件下最大。同时进行三极刺激时的阈值变化略小于双极刺激，且不像单极刺激那样受双通道刺激时间的强烈影响。受试者在临床言语测试中的表现与三极阈值的通道间变异性相关，即变异性越大，表现越差。数据表明，具有高阈值的三极通道可能揭示了神经元存活率低或电极放置不佳的耳蜗区域。
