Waisman Center, University of Wisconsin-Madison, Madison, WI, USA.
Department of Physiology and Biophysics, University of Colorado Anschutz Medical School, Aurora, CO, USA.
Trends Hear. 2024 Jan-Dec;28:23312165241229880. doi: 10.1177/23312165241229880.
Bilateral cochlear implants (BiCIs) result in several benefits, including improvements in speech understanding in noise and sound source localization. However, the benefit bilateral implants provide among recipients varies considerably across individuals. Here we consider one of the reasons for this variability: difference in hearing function between the two ears, that is, interaural asymmetry. Thus far, investigations of interaural asymmetry have been highly specialized within various research areas. The goal of this review is to integrate these studies in one place, motivating future research in the area of interaural asymmetry. We first consider bottom-up processing, where binaural cues are represented using excitation-inhibition of signals from the left ear and right ear, varying with the location of the sound in space, and represented by the lateral superior olive in the auditory brainstem. We then consider top-down processing via predictive coding, which assumes that perception stems from expectations based on context and prior sensory experience, represented by cascading series of cortical circuits. An internal, perceptual model is maintained and updated in light of incoming sensory input. Together, we hope that this amalgamation of physiological, behavioral, and modeling studies will help bridge gaps in the field of binaural hearing and promote a clearer understanding of the implications of interaural asymmetry for future research on optimal patient interventions.
双侧人工耳蜗植入 (BiCIs) 带来了多种益处，包括改善噪声环境下的言语理解能力和声源定位能力。然而，双侧植入对不同个体的受益程度存在很大差异。本文考虑了造成这种差异的原因之一：即双耳间听力功能的差异，也就是两耳间的不对称性。到目前为止，对两耳间不对称性的研究在各个研究领域都非常专业。本文的目的是将这些研究整合到一起，为两耳间不对称性领域的未来研究提供动力。我们首先考虑自下而上的处理，其中双耳线索通过来自左耳和右耳的信号的兴奋-抑制来表示，其随声音在空间中的位置而变化，并由听觉脑干中的外侧上橄榄核表示。然后我们考虑通过预测编码进行的自上而下的处理，该处理假设感知源自基于上下文和先前感觉经验的期望，由一系列级联的皮质电路表示。一个内部的、感知的模型根据传入的感觉输入进行维护和更新。我们希望，这种生理学、行为学和建模研究的结合将有助于弥合双耳听觉领域的差距，并更清楚地了解两耳间不对称性对未来最佳患者干预研究的影响。
