BRAINSTEM PROCESSING OF BINAURAL INFORMATION

这项研究的重点是神经机制，通过它 来自两个耳朵的信息被处理以增强方向性 听觉和听觉图像的形成。两只耳朵提供大脑 具有在声音中起重要作用的双耳信息 本地化，提高听力敏感度，并有助于辨别 针对背景噪声的信号。听觉系统如何利用 典型声学环境中的双耳提示，其中每个信号 耳朵一直在波动吗？普通声学的动态性质 刺激降低了双耳线索的神经处理能力，或造成了动态反应 功能提供了更多信息？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- 改变信号并计算瞬时耳间时间和电平 不同的线索来组合一个运动图像，还是有专门的 处理耳间时间变化的神经机制 暗示？ 这些问题将通过细胞外单个神经元记录来解决 在麻醉的猫和沙土鼠身上。这些实验将记录下 单个神经元对含有双耳特征的刺激的反应 表观运动：耳间振幅和相位的持续变化 差距。以前的文学作品都强调了尖锐的听觉交互作用 中枢听觉系统视差调谐作为神经证据 声源方向的选择性。然而，我们的数据(一些已公布的， 一些初步的)表明，在动态双耳条件下 较高的听觉系统可能会损害其绝对的方向敏感性 有利于提高对耳间差异变化的敏感度。这 行为可能通过基于代码的分层转换而产生 关于双耳首位置的离散方向选择性 会聚(上橄榄复合体)，或可能表明 已建立的理论来解释以下情况下的耳间差异处理 差异不是恒定的条件。建议数 实验就是为了解决这一冲突而设计的。这项研究计划 将不仅有助于指定声音信号的特征，而且 最突出的是神经整合的双耳信息，但也 一些动态处理约束：与以下两者相关的问题 健康的听众和患有单侧耳聋的人。

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.