Developmental Studies of Sound Localization Mechanisms

描述（由申请人提供）：本项目的长期目标是 了解用于确定的声学线索的同时发展 声源的空间位置和上行神经回路 编码这些线索的听觉通路。定位的所有声音线索 可以在头部相关传递函数（HRTF）的测量中捕获， 包含三个主要的定位线索，耳间时间差异， （ITD）和水平（ELD）和单声道频谱线索。成立以来 线索是由头部和脊椎的线性尺寸，相对 线索的大小将随着头部和耳廓的增长而变化 在发展过程中。拟议的实验包括两个具体目标， 为了验证一个假设，即在一个发展过程中， 声音定位的声音线索，ILD，有一个伴随的发展 外侧上级橄榄（LSO）中单个细胞的能力， 双耳交互的上行听觉通路中的第一个位点， 编码ILD。具体目标我将测试的假设，即价值的 定位线索将以可从增加的维度预测的方式改变 在发育过程中的头部和脊椎。为了实现这一点，空间的HRTF 前半球水平和垂直平面的位置， 从出生后约1周到成年的小猫以及 将测量头部和脊柱的物理尺寸。具体目标II 将检验由LSO细胞编码的ILD范围将 在发展过程中的增加与预期的幅度增加， 物理ILD，如目标I中所测量。单身能力的培养 LSO中的细胞编码ILD的能力和内侧核中细胞的能力 的梯形体，提供抑制输入的LSO，编码 将研究声级。这些研究将决定是否以及多久， 在双耳听觉系统的上升核可以补偿的变化 发展变化所带来的声学环境 头部和颈部的声学特性。

DESCRIPTION (provided by applicant): The long-term goals of this project are to understand the concurrent development of the acoustical cues used to determine the spatial location of sound sources and the neural circuits in the ascending auditory pathways that encode these cues. All acoustical cues for localization can be captured in measurements of head related transfer functions (HRTFs), which contain the three main localization cues, interaural differences in time (ITDs) and level (ELDs) and monaural spectral cues. Since the formation of the cues is governed by the linear dimensions of the head and pinnae, the relative magnitudes of the cues will change with increasing growth of the head and pinnAe during development. The proposed experiments comprise two specific aims designed to test the hypothesis that over the course of the development of one of the acoustical cues for sound localization, ILDs, there is a concomitant development of the ability of single cells in the lateral superior olive (LSO), one of the first sites in the ascending auditory pathway for binaural interaction, to encode ILDs. Specific Aim I will test the hypothesis that the values of the localization cues will change in ways predictable from the increasing dimensions of the head and pinnae during development. To accomplish this, HRTFs for spatial locations in the horizontal and vertical planes in the frontal hemisphere in kittens aged from approximately 1 week postnatal to adult as well as the physical dimensions of the head and pinnae will be measured. Specific Aim II will test the hypothesis that the range of ILDs encoded by LSO cells will increase during development with the expected increase in the magnitudes of the physical ILDs, as measured in Aim I. The development of the ability of single cells in the LSO to encode ILDs and the ability of cells in the medial nucleus of the trapezoid body, which provide the inhibitory input to the LSO, to encode sound level will be studied. These studies will determine if and how long the nuclei in the ascending binaural auditory system can compensate for changes in the acoustical environment brought about by developmental changes in the acoustical properties of the head and pinnae.