Neural coding of sound location under normal and impaired hearing conditions

正常和听力受损条件下声音位置的神经编码

• 批准号: 8995652
• 负责人: MITCHELL LEE DAY
• 金额: $ 15.05万
• 依托单位: OHIO UNIVERSITY ATHENS
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-07 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8995652
• 关键词: Acoustic Trauma; Address; Animals; Auditory; Auditory Brainstem Responses; Auditory system; Bilateral; Bilateral Hearing Loss; Binaural; Brain; Brain Stem; Cell Nucleus; Code; Comprehension; Cues; Data; Ear; Environment; Health; Hearing; Human; Individual; Inferior Colliculus; Location; Measures; Modality; Neurons; Noise; Oryctolagus cuniculus; Pattern; Performance; Population; Process; Property; Psychophysics; Scientist; Sensorineural Hearing Loss; Sensory; Sound Localization; Source; Speech; Stimulus; Testing; Time; Training; auditory pathway; awake; base; early onset; hearing impairment; interest; neuromechanism; relating to nervous system; research study; response; sensory system; sound

DESCRIPTION (provided by applicant): The binaural cues used to localize sound in the horizontal plane (i.e., azimuth) and the neural mechanisms by which these cues are encoded in the responses of neurons in the central auditory system are well known. What remains unclear is how the combined responses across neurons that are sensitive to ITD and ILD form a neural representation of azimuthal location that is robust to changes in natural auditory scenes. This proposal focuses on how the population response of neurons in the inferior colliculus (IC) encodes sound source azimuth with respect to two of these changes: 1) with changes in sound level, and 2) in the presence of a competing sound source. The third aim investigates changes in the population encoding of azimuth brought about by sensorineural hearing loss (SNHL). These aims will be addressed by collecting azimuth tuning functions from single-unit recordings in the IC of awake rabbits. Population IC responses will be used to train and test a maximum-likelihood decoder of source azimuth as a means to both evaluate the azimuth encoding ability of population activity, and to test whether patterns of population activity specific to source azimuth are robust to changes in other sound parameters (e.g., sound level). Experiments in Aim 1 will use azimuth tuning functions collected at multiple sound levels to test whether performance of the decoder is invariant to sound level; or in other words, whether the location-specific patterns of activity across IC neurons (or a subpopulation of neurons) remain largely similar between sound levels. Experiments in Aim 2 will investigate the neural coding of sound location in a multisource environment with different sound source onsets. When the onset of one sound source precedes another, IC neurons may adapt to the early-onset source and "unmask" azimuth information for the later arriving source. To test this hypothesis, azimuth tuning functions will be collected under target-alone and target-plus-interferer conditions (both simultaneous and onset difference). The decoder will be used to assess invariance of IC activity patterns when trained on target-alone data and tested on target-plus- interferer data. Finally, experiments in Aim 3 will test whether or not the azimuth encoding of IC neurons is degraded in rabbits with bilateral SNHL-the leading form of permanent hearing loss. SNHL will be induced in rabbits via high-level noise exposure. Following verification of permanent hearing loss two weeks after exposure, azimuth tuning functions will be measured in the IC. Decoder performance will be compared between noise-exposed rabbits and unexposed rabbits to evaluate whether there is a decrease in the ability of IC neurons to encode source azimuth following SNHL. Azimuth tuning will also be measured under conditions where only interaural time difference or interaural level difference varies with azimuth to assess any specific deficit i the neural representation of either binaural cue.

描述（由申请人提供）：用于在水平面（即方位）定位声音的双耳线索以及这些线索在中枢听觉系统神经元反应中编码的神经机制是众所周知的。目前尚不清楚的是，对ITD和ILD敏感的神经元之间的联合反应是如何形成方位位置的神经表征的，这种神经表征对自然听觉场景的变化具有很强的适应性。本研究主要关注下丘（IC）神经元的群体反应如何根据以下两种变化对声源方位进行编码：1)声级变化，2)存在竞争声源。第三个目的是研究感音神经性听力损失（SNHL）引起的方位群体编码的变化。这些目标将通过收集清醒兔IC中单单元记录的方位调谐函数来解决。种群IC响应将用于训练和测试源方位角的最大似是解码器，作为评估种群活动方位角编码能力的一种手段，并测试特定于源方位角的种群活动模式是否对其他声音参数（例如声级）的变化具有鲁强性。Aim 1中的实验将使用在多个声级收集的方位调谐函数来测试解码器的性能是否随声级不变；或者换句话说，IC神经元（或神经元亚群）的特定位置活动模式是否在不同的声音水平之间保持基本相似。Aim 2的实验将研究具有不同声源启动的多源环境中声音定位的神经编码。当一个声源出现在另一个声源之前时，IC神经元可能会适应早出现的声源，并为晚到达的声源“揭开”方位信息。为了验证这一假设，将在目标单独和目标加干扰条件下（同时和开始差）收集方位角调谐函数。解码器将用于评估在目标单独数据上训练和在目标加干扰数据上测试时IC活动模式的不变性。最后，Aim 3的实验将测试双侧snhl（永久性听力损失的主要形式）兔的IC神经元方位编码是否退化。高水平噪声暴露会诱发兔SNHL。在暴露两周后验证永久性听力损失后，将在IC中测量方位角调谐功能。将比较噪声暴露兔和未暴露兔的解码器性能，以评估SNHL后IC神经元编码源方位角的能力是否降低。方位角调谐也将在只有耳间时差或耳间水平差随方位角变化的情况下进行测量，以评估双耳线索的神经表征中的任何特定缺陷。

项目成果

Paired measurements of cochlear function and hair cell count in Dutch-belted rabbits with noise-induced hearing loss.

对患有噪声性听力损失的荷兰兔的耳蜗功能和毛细胞计数进行配对测量。

• DOI: 10.1016/j.heares.2019.107845
• 发表时间: 2020
• 期刊: Hearing research
• 影响因子: 2.8
• 作者: Haragopal,Hariprakash;Dorkoski,Ryan;Johnson,HollyM;Berryman,MarkA;Tanda,Soichi;Day,MitchellL
• 通讯作者: Day,MitchellL

Specific loss of neural sensitivity to interaural time difference of unmodulated noise stimuli following noise-induced hearing loss.

噪声引起的听力损失后，神经对未调制噪声刺激的耳间时间差的敏感性发生特定损失。

• DOI: 10.1152/jn.00349.2020
• 发表时间: 2020
• 期刊: Journal of neurophysiology
• 影响因子: 2.5
• 作者: Haragopal,Hariprakash;Dorkoski,Ryan;Pollard,AustinR;Whaley,GarethA;Wohl,TimothyR;Stroud,NoelleC;Day,MitchellL
• 通讯作者: Day,MitchellL