Encoding of Vocal Signals in the Auditory System

硬骨鱼外周听觉系统雌激素依赖性可塑性的发现 为建立细胞、分子和神经生理机制提供了理想的模型。 导致海选的类固醇调节。女学员鱼用多重和声 雄性的发声(嗡嗡声)用于配偶定位，并表现出戏剧性的生殖状态-- 第八神经传入对雄性嗡嗡声编码的依赖性变化 球囊，硬骨鱼的主要外周听觉器官。因此，主要的球囊传入神经 与非生殖性雌性相比，生殖性雌性表现出最佳 频率和时间编码精度的提高(通过锁相)到上 男性哼唱的和声。17|3-雌二醇或睾酮治疗非生殖女性 3-5周诱导生殖雌性的听觉表型增强，符合 转录依赖的事件。观察到的变化很可能完全是由于雌激素引起的 在有生殖能力的雌性体内循环水平高出两倍。此外，听觉神经节细胞 邻近球囊的毛细胞层表达将睾酮转化为 雌激素，因此可以使循环中的睾酮芳香化，以增加当地可获得的 雌激素的来源。 两个特定的目标将研究雌激素依赖的分子(钾通道和 雌激素受体)和神经生理(毛细胞和初级传入编码)机制 可以通过听觉系统中的锁相来改善时间处理。这个 拟议的研究还将描绘与变化相关的感觉神经可塑性的机制。 与年龄相关的荷尔蒙状态，包括生殖周期中听力的变化 在临床症状中与激素分泌的异常模式有关(例如，特纳氏病 最后，拟议的实验将导致对如何 声音信号的时间编码方面的缺陷，取决于锁相机制， 在人类中观察到的听力障碍，包括那些患有听力障碍的人； 神经病/动态同步性..‘-.’……

The discovery of estrogen-dependent plasticity in the peripheral auditory system of teleost fish provides an ideal model for establishing the cellular, molecular and neurophysiological mechanisms leading to steroid modulation of audition. Female midshipman fish use the multi-harmonic vocalizations ("hums") of males for mate localization and exhibit dramatic reproductive state- dependent shifts in the encoding of the male's hum by eighth nerve afferents that innervate the saccule, the main peripheral auditory organ in teleosts. Thus, the primary saccular afferents of reproductive females, compared to those of non-reproductive females, show an increase in best frequency and improvement in the precision of temporal encoding (via phase-locking) to the upper harmonics of male hums. Either 17|3-estradiol or testosterone treatment of non-reproductive females for 3-5 weeks induces the enhanced auditory phenotype of reproductive females, consistent with transcriptionally-dependent events. The observed changes are likely entirely due to estrogen that circulates at two fold higher levels in reproductive females. In addition, auditory ganglion cells adjacent to the saccule's hair cell layer express the enzyme aromatase that converts testosterone.to estrogen, and can therefore aromatize circulating testosterone to augment the locally available source of estrogen. Two specific aims will investigate estrogen-dependent shifts in molecular (potassium channels and estrogen receptors) and neurophysiological (hair cell and primary afferent encoding) mechanisms that can lead to improvements in temporal processing via phase-locking in the auditory system. The proposed studies will also delineate mechanisms of sensorineural plasticity that are relevant to shifts in age-related hormonal states, including changes in audition that occur during the reproductive cycle and in clinical syndromes"associatedwith abnormal patterns of hormone secretion (e.g., Turner's Syndrome)..Lastly, the proposed experiments will lead to a more fundamental understanding of how deficits in the temporal encoding of acoustic signals, dependent on phase-locking mechanisms, contribute to impairments in hearing observed among humans including those .with auditory; neuropathy/dys-synchrony.. '-.'¿......