Cortical Representation of Auditory Space

描述(申请人提供)：听力受损的人表示，他们最大的残疾之一是无法将感兴趣的声音从复杂的听觉场景中分离出来。在听力正常的听者中，声音分离通过相关声源的本地化(S)、空间解除掩蔽和空间流分离来增强。通过在人类和猫身上进行密切协调的心理物理研究，结合猫在麻醉和清醒状态下的皮质记录，将检查这三个方面的空间听力的皮质底物。特定目标1测试了这样一种假设，即与注意力不集中时相比，当猫积极从事定位任务时，皮质神经元的空间选择性增强。此外，它将检验这样的假设，即这种任务依赖的空间选择性的锐化在已被证明是正常声音定位行为所必需的皮质区域中得到增强。具体目标2将定义从掩蔽中释放空间的皮质机制。它将表征能量掩蔽的空间释放，并将开发一种新的信息掩蔽动物模型。它将检验这样一种假设，即信息掩蔽发生在听觉皮质水平，空间掩蔽释放在听觉皮质带区域增强。具体目标3开发了一种在大脑皮层水平研究空间流分离的动物模型。它测试了这样一种假设，即感知上分离的流对应于离散的激活神经元群体。此外，它还检验了一个假设，即专用于空间流分离的皮质区域与专用于声音定位的皮质区域是不同的。所有三个特定的目标都将区分皮质下机制和皮质机制，并将测试空间听力的特定方面是否由不同的皮质区域调节。这将有助于空间听力障碍的诊断和治疗。目标2和目标3将分离和量化特定的低频和高频空间线索对空间释放和空间流分离的贡献。对低频精细结构线索和高频声级线索的相对重要性的理解将有助于设计声音处理方案，旨在增强助听器和人工耳蜗使用者在复杂听觉场景中的听力。

DESCRIPTION (provided by applicant): Hearing-impaired individuals indicate as one of their greatest disabilities the inability to segregate sounds of interest from a complex auditory scene. In normal-hearing listeners, sound segregation is enhanced by localization of the relevant sound source(s), by spatial release from masking, and by spatial stream segregation. The cortical substrates of these three aspects of spatial hearing will be examined using closely coordinated psychophysical studies in humans and cats combined with cortical recording from cats in anesthetized and awake-behaving conditions. Specific Aim 1 tests the hypothesis that the spatial selectivity of cortical neurons is sharpened when a cat is actively engaged in a localization task compared to when it is inattentive. Further, it will test the hypothesis that such task-dependent sharpening of spatial selectivity is enhanced in particular cortical areas that have been shown to be necessary for normal sound localization behavior. Specific Aim 2 will define the cortical mechanisms for spatial release from masking. It will characterize spatial release from energetic masking and will develop a novel animal model for informational masking. It will test the hypothesis that informational masking arises at the level of auditory cortex and that spatial masking release is enhanced in auditory cortical belt areas. Specific Aim 3 develops an animal model for study of spatial stream segregation at the cortical level. It tests the hypothesis that perceptually segregated streams correspond to discrete populations of activated neurons. In addition, it tests the hypothesis that cortical areas that are specialized for spatial stream segregation are distinct from those specialized for sound localization. All three specific aims will discriminate between sub-cortical and cortical mechanisms and will test whether particular aspects of spatial hearing are mediated by distinct cortical areas. This will aid in diagnosis and treatment of spatial hearing disorders. Aims 2 and 3 will isolate and quantify the contribution of specific low- and high-frequency spatial cues to spatial release from masking and to spatial stream segregation. Understanding of the relative importance of low-frequency fine- structure cues and high-frequency sound-level cues will inform design of sound processing schemes intended to enhance hearing in complex auditory scenes by users of hearing aids and cochlear implants.