Developmental Studies of Sound Localization Mechanisms

描述(由申请人提供)：本项目的长期目标是 理解用于确定的声学提示的同时发展 上行通道中声源的空间位置和神经回路 对这些线索进行编码的听觉通路。用于定位的所有声学提示 可以在与头部相关的传递函数(HRTF)的测量中捕获， 它包含三个主要的定位线索，两耳之间的时差 (ITDS)、电平(ELD)和单声道光谱提示。自成立以来， 线索是由头部和羽片的线性尺寸控制的，相对的 线索的大小会随着头部和羽片的生长而改变 在开发过程中。拟议的实验包括两个设计的具体目标 来检验这一假设，即在其中一个的发展过程中 声音定位的声学提示，ILDS，有一个伴随而来的发展 在外侧上橄榄(LSO)中，单细胞的能力 在双耳相互作用的上升听觉通路中的第一个位置， 对ILD进行编码。具体目标我将检验这样的假设： 本地化线索将以可从不断增加的维度预测的方式发生变化 头部和羽片在发育过程中的位置。为了实现这一点，针对空间的HRTF 额半球水平面和垂直面的位置 从出生后大约一周到成年的小猫，以及 将测量头部和耳廓的物理尺寸。特定目标II 将测试由LSO信元编码的ILD的范围将 在开发过程中增加，预计将增加 AIM中测量的物理ILDS I.单项能力的发展 LSO中的细胞编码ILDS和内侧核细胞的能力 为LSO提供抑制输入的梯形小体的编码 将对音量进行研究。这些研究将确定是否以及多久 上升双耳听觉系统中的核团可以补偿 城市发展变化带来的声学环境 头部和耳廓的声学特性。

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.