CORTICAL REPRESENTATION OF AUDITORY SPACE

描述（由申请人提供）：定位是听力的一项基本任务。在高等哺乳动物中，听觉皮层的正常功能对正常的声音定位至关重要。尽管研究很活跃，但大脑皮层空间表征的基本原理仍然未知。拟议的实验将扩展PI实验室的观察结果，表明单个皮质神经元的时间放电模式可以全景地指示声音的位置，这意味着任何声源的位置都是由广泛分布的神经群代表的。具体目的1将评估空间编码在听觉皮层领域的专业化。以前对猫的研究主要集中在Al、A2和AES区域，没有发现任何定性的专业化。其他尚未开发的区域显示出双耳和频率特异性，似乎特别有利于空间选择性，我们的初步结果显示PAF区域的空间选择性增强。我们将测试皮层区域PAF和区域Al的背侧部分专门用于空间表征的假设。特异性目标2将对比猫皮层神经元在麻醉、空闲、视觉检测和听觉辨别条件下的听觉空间选择性。我们将测试一个假设，即神经脉冲模式的位置特异性在清醒的动物中得到增强，特别是当动物从事听觉任务时。具体目标3将探索人类听众从声音光谱中提取位置线索的规则。我们将采用一种新的程序来表征导致特定高度判断的近端刺激谱。我们将区分假设的宽带和单特征机制，并确定识别频谱定位线索的频率分辨率水平。特异性目标4将把皮质神经元的升高敏感性与其频率响应区域的特征联系起来。我们将测试这一假设，即兴奋和抑制域的特定配置是光谱定位线索检测的基础。这项研究将提供对听觉皮层机制的基本理解，这是评估颞叶病理和设计损伤和疾病治疗反应所需要的。

DESCRIPTION (provided by applicant): Localization is a fundamental task of hearing. In higher mammals, normal function of the auditory cortex is essential for normal sound localization. Despite active research, basic principles of spatial representation in the cortex remain unknown. Proposed experiments will extend observations from the PI's laboratory that indicate that the temporal firing patterns of single cortical neurons can signal the locations of sounds panoramically, implying that the location of any sound source is represented by widely distributed neural populations. Specific Aim 1 will evaluate specialization for spatial coding among auditory cortical fields. Previous studies in cats, focusing on areas Al, A2, and AES, have not discovered any qualitative specialization. Other as yet unexplored areas show binaural and frequency specificity that seem particularly conducive to spatial selectivity, and our preliminary results show enhanced spatial selectivity in area PAF. We will test the hypothesis that cortical areas PAF and the dorsal part of area Al are specialized for spatial representation. Specific Aim 2 will contrast auditory spatial selectivity in cat cortical neurons during anesthetized, idle, visual-detection, and auditory-discrimination conditions. We will test the hypothesis that location specificity of neural spike patterns is enhanced in awake animals, particularly when the animal is engaged in an auditory task. Specific Aim 3 will explore the rules by which human listeners extract location cues from sound spectra. We will employ a new procedure that characterizes the proximal stimulus spectra that result in particular elevation judgments. We will discriminate between hypothetical broadband and single-feature mechanisms and will determine the level of frequency resolution by which spectral localization cues are recognized. Specific Aim 4 will relate elevation sensitivity of cortical neurons to characteristics of their frequency response areas. We will test the hypothesis that specific configurations of excitatory and inhibition domains underlie detection of spectral localization cues. This research will provide basic understanding of auditory cortical mechanisms that is needed for evaluation of temporal lobe pathology and for the design of therapeutic responses to injury and disease.