Hughes Michelle L, Choi Sangsook, Glickman Erin
Boys Town National Research Hospital, Lied Learning and Technology Center, 425 North 30(th) Street, Omaha, NE, 68131, USA.
Boys Town National Research Hospital, Lied Learning and Technology Center, 425 North 30(th) Street, Omaha, NE, 68131, USA.
Hear Res. 2018 Mar;359:50-63. doi: 10.1016/j.heares.2017.12.015. Epub 2017 Dec 28.
Modeling studies suggest that differences in neural responses between polarities might reflect underlying neural health. Specifically, large differences in electrically evoked compound action potential (eCAP) amplitudes and amplitude-growth-function (AGF) slopes between polarities might reflect poorer peripheral neural health, whereas more similar eCAP responses between polarities might reflect better neural health. The interphase gap (IPG) has also been shown to relate to neural survival in animal studies. Specifically, healthy neurons exhibit larger eCAP amplitudes, lower thresholds, and steeper AGF slopes for increasing IPGs. In ears with poorer neural survival, these changes in neural responses are generally less apparent with increasing IPG. The primary goal of this study was to examine the combined effects of stimulus polarity and IPG within and across subjects to determine whether both measures represent similar underlying mechanisms related to neural health. With the exception of one measure in one group of subjects, results showed that polarity and IPG effects were generally not correlated in a systematic or predictable way. This suggests that these two effects might represent somewhat different aspects of neural health, such as differences in site of excitation versus integrative membrane characteristics, for example. Overall, the results from this study suggest that the underlying mechanisms that contribute to polarity and IPG effects in human CI recipients might be difficult to determine from animal models that do not exhibit the same anatomy, variance in etiology, electrode placement, and duration of deafness as humans.
建模研究表明，极性之间神经反应的差异可能反映了潜在的神经健康状况。具体而言，极性之间电诱发复合动作电位（eCAP）幅度和幅度增长函数（AGF）斜率的巨大差异可能反映外周神经健康较差，而极性之间更相似的eCAP反应可能反映更好的神经健康状况。在动物研究中，相间间隙（IPG）也已被证明与神经存活有关。具体来说，健康的神经元随着IPG增加表现出更大的eCAP幅度、更低的阈值和更陡的AGF斜率。在神经存活较差的耳朵中，随着IPG增加，这些神经反应的变化通常不太明显。本研究的主要目的是检查刺激极性和IPG在个体内和个体间的联合效应，以确定这两种测量方法是否代表与神经健康相关的相似潜在机制。除了一组受试者中的一项测量外，结果表明极性和IPG效应通常没有以系统或可预测的方式相关。这表明这两种效应可能代表神经健康的一些不同方面，例如兴奋部位与整合膜特性的差异。总体而言，本研究结果表明，对于没有表现出与人类相同的解剖结构、病因差异、电极放置和耳聋持续时间的动物模型，可能难以确定导致人类CI接受者极性和IPG效应的潜在机制。
