Brown Carolyn J, Etler Christine, He Shuman, O'Brien Sara, Erenberg Sheryl, Kim Jae-Ryong, Dhuldhoya Aayesha N, Abbas Paul J
Department of Speech Pathology and Audiology, University of Iowa, Iowa City, Iowa 52242, USA.
Ear Hear. 2008 Oct;29(5):704-17. doi: 10.1097/AUD.0b013e31817a98af.
The purpose of this study was to determine if changes in the position of the stimulating electrode in the cochlea could be used to elicit the electrically evoked auditory change complex (EACC) from Nucleus cochlear implant users.
Nine postlingually deafened adults participated in this study. Each study participant had been using his or her Nucleus CI24 cochlear implant for at least 3 mos before testing. The speech processor was bypassed and the output of the implanted receiver/stimulator was controlled directly. The stimulus was a 600 msec burst of a biphasic pulse train (1000 pps). In control conditions, the stimulating electrode was held constant and stimulation continued throughout the 600 msec recording interval. In experimental conditions, the EACC was elicited by introducing a change in the stimulating electrode 300 msec after the onset of the pulse train. The EACC was recorded using surface electrodes. Three recordings of 100 sweeps each were obtained for each stimulus condition. Bandpass filtering (1-100 Hz) was used to minimize contamination of the recordings by stimulus artifact. Averaged responses were then smoothed using a 40-msec wide boxcar filter and standard peak picking procedures were used to analyze these responses in the time domain.
In each case, a clear onset response (P1-N1-P2) was recorded. In the experimental conditions, a second evoked potential, the EACC, was also recorded after the change in stimulating electrode. This second response had general morphological characteristics that were very similar to those of the onset response. Increasing the separation between the two stimulating electrodes in the experimental conditions resulted in a general trend toward increased EACC amplitudes.
This report describes results of a set of experiments in which the speech processor of the cochlear implant was bypassed and the EACC was recorded in response to a change in stimulating electrode position. EACC amplitude was shown to increase as the separation between the two stimulating electrodes increased. Although preliminary in nature, these results demonstrate the feasibility of recording the EACC in response to changes in stimulating electrode position from individual cochlear implant users.
本研究的目的是确定耳蜗内刺激电极位置的改变是否可用于诱发人工耳蜗使用者的电诱发听觉变化复合体（EACC）。
9名语后聋成年人参与了本研究。每位研究参与者在测试前已使用其Nucleus CI24人工耳蜗至少3个月。绕过语音处理器，直接控制植入式接收器/刺激器的输出。刺激为600毫秒的双相脉冲串（1000次/秒）。在对照条件下，刺激电极保持恒定，并在整个600毫秒记录间隔内持续刺激。在实验条件下，在脉冲串开始后300毫秒引入刺激电极的变化来诱发EACC。使用表面电极记录EACC。每种刺激条件下均获得3组记录，每组100次扫描。采用带通滤波（1 - 100赫兹）以尽量减少刺激伪迹对记录的污染。然后使用40毫秒宽的矩形窗滤波器对平均反应进行平滑处理，并采用标准的峰值检测程序在时域分析这些反应。
在每种情况下，均记录到清晰的起始反应（P1 - N1 - P2）。在实验条件下，刺激电极改变后还记录到第二个诱发电位，即EACC。这第二个反应的一般形态特征与起始反应非常相似。在实验条件下增加两个刺激电极之间的间距会导致EACC振幅总体上有增加的趋势。
本报告描述了一组实验的结果，其中绕过了人工耳蜗的语音处理器，并记录了对刺激电极位置变化作出反应的EACC。结果表明，随着两个刺激电极之间间距的增加，EACC振幅会增大。尽管这些结果本质上是初步的，但它们证明了记录个体人工耳蜗使用者对刺激电极位置变化作出反应的EACC的可行性。
