Department of Speech and Hearing Sciences, University of Washington, Seattle, Washington.
Center for Neural Science, New York University, New York, New York.
J Neurophysiol. 2019 Sep 1;122(3):1110-1122. doi: 10.1152/jn.00057.2019. Epub 2019 Jul 17.
The auditory brain stem response (ABR) is an evoked potential that indexes a cascade of neural events elicited by sound. In the present study we evaluated the influence of sound frequency on a derived component of the ABR known as the binaural interaction component (BIC). Specifically, we evaluated the effect of acoustic interaural (between-ear) frequency mismatch on BIC amplitude. Goals were to ) increase basic understanding of sound features that influence this long-studied auditory potential and ) gain insight about the persistence of the BIC with interaural electrode mismatch in human users of bilateral cochlear implants, presently a limitation on the prospective utility of the BIC in audiological settings. Data were collected in an animal model that is audiometrically similar to humans, the chinchilla (; 6 females). Frequency disparities and amplitudes of acoustic stimuli were varied over broad ranges, and associated variation of BIC amplitude was quantified. Subsequently, responses were simulated with the use of established models of the brain stem pathway thought to underlie the BIC. Collectively, the data demonstrate that at high sound intensities (≥85 dB SPL), the acoustically elicited BIC persisted with interaurally disparate stimulation (click frequencies ≥1.5 octaves apart). However, sharper tuning emerged at moderate sound intensities (65 dB SPL), with the largest BIC occurring for stimulus frequencies within ~0.8 octaves, equivalent to ±1 mm in cochlear place. Such responses were consistent with simulated responses of the presumed brain stem generator of the BIC, the lateral superior olive. The data suggest that leveraging focused electrical stimulation strategies could improve BIC-based bilateral cochlear implant fitting outcomes. Traditional hearing tests evaluate each ear independently. Diagnosis and treatment of binaural hearing dysfunction remains a basic challenge for hearing clinicians. We demonstrate in an animal model that the prospective utility of a noninvasive electrophysiological signature of binaural function, the binaural interaction component (BIC), depends strongly on the intensity of auditory stimulation. Data suggest that more informative BIC measurements could be obtained with clinical protocols leveraging stimuli restricted in effective bandwidth.
听觉脑干反应（ABR）是一种诱发电位，它反映了一系列由声音引发的神经事件。在本研究中，我们评估了声音频率对 ABR 的一个衍生成分，即双耳相互作用成分（BIC）的影响。具体来说，我们评估了声觉两耳（耳间）频率失配对 BIC 幅度的影响。研究目的是：1）增进对影响这种长期研究的听觉电位的声音特征的基本了解；2）深入了解在双侧人工耳蜗使用者中，由于两耳电极失配导致的 BIC 持久性，这是目前 BIC 在听力学环境中的潜在应用的一个限制。数据是在与人类相似的听觉模型——南美栗鼠（6 只雌性）中收集的。声刺激的频率差异和幅度在很宽的范围内变化，同时量化了 BIC 幅度的相关变化。随后，使用被认为是 BIC 基础的脑干通路的既定模型模拟了反应。总的来说，数据表明，在高声音强度（≥85dB SPL）下，双耳刺激的声学诱发 BIC 仍然存在（点击频率相隔≥1.5 个倍频程）。然而，在中等声音强度（65dB SPL）下出现了更尖锐的调谐，最大的 BIC 发生在刺激频率约为 0.8 个倍频程内，相当于耳蜗位置的±1mm。这些反应与假定的 BIC 脑干发生器的模拟反应一致，即外侧上橄榄。数据表明，利用集中的电刺激策略可以改善基于 BIC 的双侧人工耳蜗适配结果。传统的听力测试评估每个耳朵的听力情况。双耳听力障碍的诊断和治疗仍然是听力临床医生的一个基本挑战。我们在动物模型中证明，非侵入性双耳功能的电生理特征，即双耳相互作用成分（BIC）的预期效用，强烈依赖于听觉刺激的强度。数据表明，利用限制有效带宽的刺激，临床方案可以获得更有信息量的 BIC 测量。
