Encoding of vocal Signals in the Auditory System

描述(申请人提供)：这里提出的研究的中心目标是了解脊椎动物的听觉系统如何能够识别和解释大量物种-典型的声音交流信号。声音交流并不是人类独有的，而是许多非哺乳动物脊椎动物的共同特征。这里的重点是声音的产生！硬骨鱼发声，提供了识别神经操作基本原理的模型系统，这些基本原理导致了包括人类在内的哺乳动物复杂听觉系统的进化。发出声音的硬骨鱼有一个简单的物种曲目-典型的信号对它们的社会和生殖行为至关重要。这些信号可以很容易地复制，个体对自然或计算机合成信号的回放产生刻板印象的行为反应。硬骨鱼也有一个类似于包括哺乳动物在内的陆生脊椎动物的中枢听觉系统。我们认为，普氏实习鱼(Porichthys Notatus)具有发声和声学行为，以及潜在的神经编码机制和电路，这些都是解决挑战所有脊椎动物的声学问题的必要条件和充分条件。尤其是军校鱼，产生具有高度不同身体属性的广告和激动型发声。雄性用持续时间长的哼唱向雌性求爱(秒-L h)，并表现出基本平坦的包络，由低基频(90-100赫兹)和几个谐波组成。相反，雄性也通过包络调制发出激动性信号，即以2-3赫兹的间隔发出短暂(50-200ms)的咕噜声(咕噜声具有类似哼唱的FOS)。当两只雄鸟的嗡嗡声重叠时，也会引入包络调制，以产生由两个FOS的不同决定的小差异频率(0-8赫兹)的声学节拍。行为学研究表明，个别学员根据信号持续时间、信号之间的静默间隙和包络调制程度来区分嗡嗡声和非嗡嗡声(节拍和咕噜声-HKE脉冲串)。三个具体目标将调查听觉机制如何为嗡嗡声和非嗡嗡声的行为分类提供神经基础。目标1使用生理测量(尖峰频率和同步)和模拟自然发声的刺激来研究脑干编码机制，以将声音信号分类为嗡嗡声或非嗡嗡声。Aim 2将这些神经生理指标与细胞外和细胞内的染料标记相结合，以描绘Aim 1中确定的神经元的功能回路。Aim 3将研究负责外周和中枢听觉系统差异处理的季节性、生殖状态依赖的可塑性。

DESCRIPTION (provided by applicant): The central goal of the research proposed here is to understand how the vertebrate auditory system is able to recognize and interpret an enormous repertoire of species-typical vocal communication signa's. Sound communication is not unique to humans, but rather is a trait shared with many non-mammalian vertebrates. The focus here is on sound producing! vocalizing teleost fish that provide model systems to identify the basic principles of neural operation that have lead to the evolution of the complex auditory system of mammals, including humans. Vocalizing teleosts have a simple repertoire of species-typical signals central to their social and reproductive behavior. These signals can be easily reproduced and individuals produce stereotyped behavioral responses to playbacks of natural or computer-synthesized signals. Teleosts also have a central auditory system resembling that of terrestrial vertebrates including mammals. We propose that the plainfin midshipman fish (Porichthys notatus) has the vocal and acoustic behaviors, and underlying neural encoding mechanisms and circuitry, both necessary and sufficient to solve acoustic problems that challenge all vertebrates. Midshipman fish, in particular, produce advertisement and agonistic vocalizations with highly divergent physical attributes. Males acoustically court females using hums that are long duration (secs-l h) and exhibit an essentially flat envelope consisting of a low fundamental frequency (90-100 Hz) and several harmonics. In contrast, males also emit agonistic signal with envelope modulations, namely brief (50-200 ms) grunts at intervals of 2-3 Hz (grunts have FOs like hums). Envelope modulations are also introduced when the hums of two males overlap to produce an acoustic beat with a small difference frequency (0-8 Hz) determined by the difference in the two FOs. Behavioral studies show that individual midshipman distinguish hums from non-hums (beats and grunt-hke pulse trains) based on signal duration, silent gaps between signals and the degree of envelope modulation. Three specific aims will investigate how auditory mechanisms provide a neural basis for the behavioral categorization of hums from non-hums. Aim 1 uses physiological measures (spike rate and synchronization) and stimuli that mimic natural vocalizations to investigate brainstem encoding mechanisms for categorizing acoustic signals as either hums or non-hums. Aim 2 will couple these neurophysiological measures with extracellular and intracellular dye labeling to delineate the functional circuitry of the neurons identified in Aim 1. Aim 3 will investigate seasonal, reproductive state-dependent plasticity responsible for differential processing in the peripheral and central auditory systems.