Cortical Sensitivity to Acoustic Cues for Sound Location

皮质对声音提示的敏感性以进行声音定位

• 批准号: 6795163
• 负责人: EWAN A MACPHERSON
• 金额: $ 7.59万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6795163
• 关键词: auditory cortex; auditory discrimination; auditory stimulus; behavioral /social science research tag; cats; cues; neurophysiology; neuropsychology; psychoacoustics; sound perception

DESCRIPTION (provided by applicant): Sound localization is a fundamental task of the auditory system, and in higher mammals, requires an intact auditory cortex. Many cortical neurons respond over broad regions of space and vary the rate and temporal pattern of their spiking activity with changes in the location of a sound source. The ultimate objective of the proposed studies is to understand the nature and origin of this representation of auditory space in the mammalian auditory cortex. The proposed experiments will address, using an anesthetized cat preparation, how these representations are derived from units' sensitivities to various individual spatial cues and how these sensitivities vary among cortical areas. Specific Aim 1 will evaluate the individual contributions of interaural time difference (ITD), interaural level-difference (ILD), and monaural spectral cues to the azimuthal sensitivity of neurons in different fields of the auditory cortex. We will test the hypothesis that ILD, and not ITD or monaural spectral shape, is the dominant contributor to azimuth sensitivity in cat auditory cortex. Experiments will estimate the relative importance of various potential azimuthal location cues using free-field stimulation and virtual auditory space (VAS) stimulation, which permits independent control of the sound at each ear. VAS stimuli will use each animal's individual head-related transfer functions, and will be delivered with a transaural system that will allow direct comparison of free-field and VAS stimulation of the same neurons. Specific Aim 2 will evaluate whether elevation-sensitive neurons in the auditory cortex encode space or merely spectrum. Spatial cues in the vertical dimension are provided by the location-dependent filtering action of the head and pinna. Human listeners can accurately localize noises with a variety of non-flat, wideband spectral profiles. Elevation-sensitive units in auditory cortex have been found, but because their sensitivity was measured using only flat-spectrum source spectra, it is unknown whether such units maintain spatial constancy over changes in source spectra, or whether they merely encode the spectrum of the stimulus at the eardrum. Experiments will evaluate the degree to which neurons' location-related responses are conserved when the source spectrum is varied among a set of wideband, but non-flat, spectra. This research will provide basic understanding of auditory cortical mechanisms needed for evaluation of temporal lobe pathology and for the design of therapeutic responses to injury and disease.

描述（由申请人提供）：声音定位是听觉系统的一项基本任务，在高等哺乳动物中，需要完整的听觉皮层。许多皮层神经元在广阔的空间区域做出反应，并随着声源位置的变化而改变其尖峰活动的速率和时间模式。拟议研究的最终目标是了解哺乳动物听觉皮层中听觉空间的这种表征的性质和起源。拟议的实验将使用麻醉猫制剂来解决这些表征如何从单位对各种个体空间线索的敏感性中得出，以及这些敏感性如何在皮质区域之间变化。具体目标 1 将评估耳间时间差 (ITD)、耳间声级差 (ILD) 和单耳频谱线索对听觉皮层不同区域神经元方位敏感性的个体贡献。我们将检验这样的假设：ILD（而不是 ITD 或单耳频谱形状）是猫听觉皮层方位敏感性的主要贡献者。实验将使用自由场刺激和虚拟听觉空间（VAS）刺激来估计各种潜在方位角位置线索的相对重要性，这允许对每只耳朵的声音进行独立控制。 VAS 刺激将使用每只动物各自的头部相关传递功能，并将通过耳听系统传递，该系统将允许直接比较相同神经元的自由场刺激和 VAS 刺激。具体目标 2 将评估听觉皮层中的海拔敏感神经元是否编码空间或仅编码频谱。垂直维度的空间线索由头部和耳廓的位置相关过滤作用提供。人类听众可以通过各种非平坦、宽带频谱轮廓准确地定位噪声。听觉皮层中的海拔敏感单元已经被发现，但由于它们的灵敏度仅使用平谱源光谱来测量，因此尚不清楚这些单元是否在源光谱变化时保持空间恒定性，或者它们是否仅对刺激的光谱进行编码在耳膜处。实验将评估当源光谱在一组宽带但非平坦光谱中变化时，神经元位置相关响应的保守程度。这项研究将为评估颞叶病理学以及设计针对损伤和疾病的治疗反应所需的听觉皮层机制提供基本了解。