Cortical Representation of Auditory Space

描述（由申请人提供）：听力受损的人表示，他们最大的残疾之一是无法从复杂的听觉场景中分离出感兴趣的声音。在听力正常的听者中，相关声源的定位、掩蔽的空间释放和空间流隔离会增强声音隔离。我们将通过对人类和猫的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层记录，来研究空间听力这三个方面的皮层基质。特异性目标1验证了这样一个假设，即当猫积极参与定位任务时，与不注意时相比，皮质神经元的空间选择性更强。此外，它将测试这样一个假设，即这种与任务相关的空间选择性锐化在特定的皮层区域得到增强，而这些区域已被证明是正常声音定位行为所必需的。特异性目标2将定义空间释放掩蔽的皮质机制。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。实验将验证信息掩蔽产生于听觉皮层水平，而空间掩蔽释放在听觉皮层带区域增强的假设。具体目标3开发了一个动物模型，用于研究皮层水平的空间流分离。它验证了感知隔离流对应于激活神经元的离散种群的假设。此外，它还验证了专门用于空间流隔离的皮质区域与专门用于声音定位的皮质区域不同的假设。所有这三个具体目标将区分皮层下和皮层机制，并将测试空间听力的特定方面是否由不同的皮层区域介导。这将有助于空间听力障碍的诊断和治疗。目标2和3将分离和量化特定的低频和高频空间信号对掩蔽和空间流分离的空间释放的贡献。了解低频精细结构线索和高频声级线索的相对重要性，将为设计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的声音处理方案提供信息。

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.