BRAINSTEM PROCESSING OF BINAURAL INFORMATION

这项研究计划的重点是通过神经元机制， 处理从两只耳朵得到的信息以增强方向性 听觉和听觉图像的形成。两只耳朵提供大脑 双耳信息在声音中起着重要作用 定位，增强听力灵敏度，并有助于区分 信号与背景噪声的对比。听觉系统如何利用 在典型的声学环境中的双耳线索， 耳朵不断波动？普通声学的动态特性 刺激降低了双耳线索的神经处理，或者动态 功能提供额外的信息？是我们对听觉的感知 通过重复采样时间的机制来调节运动- 变化的信号，并计算瞬时双耳间时间和水平 不同的线索来组合运动的图像，或者有专门的 处理耳间听觉时间变化的神经机制 线索？ 这些问题将通过细胞外单神经元记录来解决 在麻醉猫和沙鼠身上。实验将记录 单个神经元对包含双耳特征的刺激的反应 视运动：耳间振幅和相位的持续变化 差距。以前的文献强调了尖锐的耳间 中枢听觉系统的差异调谐作为神经系统的证据 声源方向的选择性。然而，我们的数据（一些已发表， 一些初步的）建议在动态双耳条件下， 较高的听觉系统可能会损害其绝对方向敏感性 有利于增强对耳间视差变化的敏感性。 这 行为可能通过基于代码的分层转换而产生， 在双耳第一个站点的离散方向选择性 会聚（上级橄榄复合体），或可能表明 建立理论来解释耳间差异处理， 差异不恒定的条件。拟议 实验旨在解决这一冲突。这个研究项目 将有助于不仅指定声学信号的特征， 最突出的是双耳信息的神经整合，但也 一些动态处理的限制： 健康的听众和单侧耳聋的人。

This research program is focused on the neuronal mechanisms through which information derived from the two ears is processed to enhance directional hearing and the formation of auditory images. Two ears provide the brain with binaural information that plays an important role in sound localization, enhances listening sensitivity and aids in discrimination of signals against background noise. How does the auditory system utilize binaural cues in typical acoustic environments where the signals at each ear fluctuate constantly? Does the dynamic nature of common acoustic stimuli degrade the neural processing of binaural cues, or do the dynamic features provide additional information? Is our perception of auditory motion mediated through mechanisms that repetitively sample the time- varying signal and calculate the instantaneous interaural time and level difference cues to assemble an image of motion, or are there specialized neural mechanisms that process the temporal variations in the interaural cues? These issues will be addressed with extracellular single neuron recording in anesthetized cats and gerbils. The experiments will document the responses of single neurons to stimuli containing binaural features of apparent motion: ongoing variation in interaural amplitude and phase disparities. Previous literature has emphasized the sharp interaural disparity tuning of the central auditory system as evidence of neural selectivity for sound source direction. However, our data (some published, some preliminary) suggest that under dynamic binaural conditions the higher auditory system may compromise its absolute directional sensitivity in favor of enhanced sensitivity to change in interaural disparity. This behavior might arise through hierarchical transformation of a code based on discrete directional selectivity at the first site of binaural convergence (the superior olivary complex), or might indicate a failure of established theory to account for interaural disparity processing under conditions where the disparities are not constant. The proposed experiments are designed to resolve this conflict. This research program will help to specify not only the features of acoustic signals that are most salient in the neural integration of binaural information, but also some of the dynamic processing constraints: issues of relevance both for healthy listeners and for those suffering unilateral deafness.