Cortical Representation of Auditory Space

描述（由申请人提供）：正常的空间听觉是听觉场景分析的关键，它有助于听众在存在竞争声音的情况下听到信号。这种能力的丧失可以说是轻度至中度听力损失患者最大的残疾之一。我们的特点是在人类心理物理学场景分析的客观措施，并已检查了一些自下而上的机制，在麻醉猫的听觉皮层。现在，我们建议检查自上而下的皮质机制的空间方面的听觉场景分析，利用密切协调的人类和猫的心理物理学与同时皮层记录在行为猫。具体目标1解决了空间流分离，通过该空间流分离，听众解开多个交织的声音序列。在麻醉条件下，皮层神经元表现出空间流分离的第一步，通过优先同步到两个竞争的声音序列中的一个或另一个从不同的源位置。那些被麻醉的神经元，当然不知道哪些序列对应于目标或掩蔽。现在，我们将测试的假设，在执行任务与皮层记录，猫的听众选择皮层模块同步到目标的声音序列，无论是通过促进模块同步到目标和/或通过抑制模块同步到掩蔽。人类和猫的心理物理学和猫的皮层生理学将评估空间敏锐度的条件下，听众参加空间或非空间隔离线索。临床报告和我们最近的研究结果表明，声音定位和空间流分离是由不同的皮层区域完成的。我们将在人类中测试这一点，通过扩展我们的观察，空间隔离和本地化显着不同的依赖于刺激条件。在猫中，我们将对比几个候选皮层区域之间的空间流分离。目标2解决了信息掩蔽的空间释放，这是通过从并发掩蔽信号中空间分离信号来改善声音接收。特别是信息掩蔽，是在信号和掩蔽物之间不存在频谱重叠的情况下发生的掩蔽。在人类和猫的心理物理学中，我们将测量给予各种掩蔽成分的试验权重，并评估各种成分和空间线索对空间释放的贡献程度。在行为猫的皮层记录，我们将量化屏蔽的神经信号检测带外频率成分和信号和掩蔽器的空间分离的影响，这些组件的拒绝。这项工作探讨了现实生活中的听觉场景分析的单耳和双耳空间线索。它将产生的结果，将通知助听器和人工耳蜗植入的声音处理策略的设计。引入的新动物模型将产生对皮层空间表征的自上而下的任务依赖性调制的新理解，从而增强空间听力障碍的诊断和治疗。

DESCRIPTION (provided by applicant): Normal spatial hearing is key to auditory scene analysis, which aids listeners in hearing out signals in the presence of competing sounds. Loss of this ability arguably is one of the greatest disabilities of people with mild-to-moderate hearin loss. We have characterized objective measures of scene analysis in human psychophysics and have examined some bottom-up mechanisms in auditory cortex in anesthetized cats. Now, we propose to examine the top-down cortical mechanisms of spatial aspects of auditory scene analysis, utilizing closely coordinated human and cat psychophysics with simultaneous cortical recordings in behaving cats. Specific Aim 1 addresses spatial stream segregation, by which listeners disentangle multiple interleaved sound sequences. In anesthetized conditions, cortical neurons exhibit the first steps of spatial stream segregation by synchronizing preferentially to one or the other of two competing sound sequences from differing source locations. Those anesthetized neurons, of course don't know which sequences correspond to target or to masker. Now, we will test the hypothesis that, during task performance with cortical recording, feline listeners select cortical modules synchronized to target sound sequences, either by facilitating modules synchronized to the target and/or by suppressing modules synchronized to the masker. Human and cat psychophysics and cat cortical physiology will evaluate spatial acuity in conditions in which listeners attend to spatial or to non-spatial segregation cues. Clinical reports and our recent results suggest that sound localization and spatial stream segregation are accomplished by different cortical areas. We will test this in humans by extending our observations that spatial segregation and localization differ markedly in their dependence on stimulus conditions. In cats, we will contrast spatial stream segregation among several candidate cortical areas. Aim 2 addresses spatial release from informational masking, which is the improvement in sound reception by spatial separation of a signal from a concurrent masker. Informational masking, in particular, is the masking that occurs in the absence of spectral overlap between signal and masker. In human and cat psychophysics, we will measure the trial-by-trial weights given to various masker components and will evaluate the degree to which various components and spatial cues contribute to spatial release. In cortical recordings from behaving cats, we will quantify masking of neural signal detection by out-of-band frequency components and the effects of spatial separation of signal and masker on rejection of such components. This work explores the monaural and binaural spatial cues for real-life auditory scene analysis. It will yield results that will inform design of sound processing strategies for hearing aids and cochlear implants. The new animal models that are introduced will yield new understanding of top-down task-dependent modulation of cortical spatial representation, enhancing diagnosis and treatment of spatial hearing deficits.