Effect of inter-phase gap on the sensitivity of cochlear implant users to electrical stimulation
Effect of inter-phase gap on the sensitivity of cochlear implant users to electrical stimulation
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DOI：
10.1016/j.heares.2005.03.021
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发表时间：
2005-07-01
期刊：
影响因子：
2.8
通讯作者：
Wouters, J
中科院分区：
文献类型：
--
作者：
Carlyon, RP;van Wieringen, A;Wouters, J
测量了施加于Nucleus CI24和Laura人工耳蜗单通道的双相脉冲序列的人类行为阈值，作为相间间隙(IPG)的函数。实验1采用双极刺激，脉冲频率为100pps，刺激持续时间为400ms。在一种情况下，每个脉冲的两个相位具有相反的极性。随着IPG从接近零增加到测试的最长值(2,900亩S，4,900亩S，劳拉)，阈值继续下降910分贝。这一时间过程比报道的动物单细胞记录要长得多。在第二种情况下，每个脉冲的两个相位具有相同的极性，其在脉冲之间交替。阈值与IPG无关，与条件1在IPG=4900亩时的阈值相似。试验2采用单极刺激。其中一个条件与试验1的条件1相似，阈值也下降到所研究的最长IPG(2900亩S)。当脉率降低到20pps时，以及每次试验中只出现一个脉冲时，也会发生这种情况。保持IPG在8亩S恒定，并在每个周期中增加一个额外的双相脉冲x毫秒，产生的阈值大致与x无关，表明在其他条件下，IPG的效果不是由于听神经中枢部位的不应性释放所致。实验3在三个IPG下测量阈值，这三个IPG小于、等于和超过连续脉冲之间间隔的一半。阈值在中间IPG时最低。所有实验的结果都可以用一个线性模型来拟合，该模型由一个基于阈值与正弦电刺激频率相关函数的低通滤波器组成。该数据和模型对降低人工耳蜗的功率消耗具有一定的指导意义。(C)2005 Elsevier B.V.保留所有权利。
Human behavioral thresholds for trains of biphasic pulses applied to a single channel of Nucleus CI24 and LAURA cochlear implants were measured as a function of inter-phase gap (IPG). Experiment 1 used bipolar stimulation, a 100-pps pulse rate, and a 400-ms stimulus duration. In one condition, the two phases of each pulse had opposite polarity. Thresholds continued to drop by 910 dB as IPG was increased from near zero to the longest value tested (2900 mu s for CI24, 4900 mu s for LAURA). This time course is much longer than reported for single-cell recordings from animals. In a second condition, the two phases of each pulse had the same polarity, which alternated from pulse to pulse. Thresholds were independent of IPG, and similar to those in condition 1 at IPG=4900 mu s. Experiment 2 used monopolar stimulation. One condition was similar to condition 1 of experiment 1, and thresholds also dropped up to the longest IPG studied (2900 mu s). This also happened when the pulse rate was reduced to 20 pps, and when only a single pulse was presented on each trial. Keeping IPG constant at 8 mu s and adding an extra biphasic pulse x ms into each period produced thresholds that were roughly independent of x, indicating that the effect of IPG in the other conditions was not due to a release from refractoriness at sites central to the auditory nerve. Experiment 3 measured thresholds at three IPGs, which were less than, equal to, and more than one half of the interval between successive pulses. Thresholds were lowest at the intermediate IPG. The results of all experiments could be fit by a linear model consisting of a lowpass filter based on the function relating threshold to the frequency of sinusoidal electrical stimulation. The data and model have implications for reducing the power consumption of cochlear implants. (c) 2005 Elsevier B.V. All rights reserved.