Central Nervous System Processing of Complex Acoustic Signals

项目摘要：在感知声学通信信号时，最重要的两个级别 中枢神经系统(CNS)必须处理的声音有(1)颞叶精细结构(TFS)--快速变化的 语音波形包络内的频率和幅度-以及(2)语音波形中的顺序模式 声学元件的结构。在人类语言中，这些能力对解码信息都很重要 从讲话和学习中准确地造出单词和句子。虽然人们已经了解了很多关于 人类的听觉皮质如何通过使用非侵入性技术计算复杂的声音信号， 目前还不知道听觉系统的神经元如何处理这些倍数的声学通信信号 级别。声乐学习鸟类及其复杂的、学习过的声乐曲目和顺序模式的歌唱 为理解大脑如何处理复杂的声学信号提供了非常好的模型。 鸣禽，如斑马雀，鹦鹉，如虎皮鹦鹉，是特别有吸引力的模特 询问CNS如何处理复杂的声音信号，因为鸟类可以听到超过TFS的水平 人类和其他哺乳动物的能力，以及TFS和序列所涉及的神经机制 对加工过程的探索很少。此外，最近的实验表明，TFS的变化是 对于斑马雀来说，比起歌曲音节顺序模式的变化，它们更容易辨别。这是在 相比之下，人类和虎皮鹦鹉的序列变化非常明显。在感知方面，编码 初级和次级听区神经元的TFS和顺序模式可能有助于解释为什么 不同物种在处理这些特征时有所不同。在声乐的单单位和多单位水平上检查这些能力 因此，学习鸟类可以帮助我们进一步了解中枢神经系统对声音通信信号的处理，以及 解决影响人类语言的中枢听觉障碍。 为了确定听觉模式识别和处理的神经基础，我提出了 以下两个具体目标：在目标1中，我将比较TFS和斑马序列模式的可区分性 鸟儿是鸣禽模型，鹦鹉是鹦鹉模型。我将让这两个听觉水平相互竞争 在使用施罗德波形的心理声学测试中，可以操纵的合成刺激，只有 TFS或元素的顺序改变，我也会获得这两个物种的听力阈值 对序列的更改。在目标2中，我将比较斑雀和虎皮鹦鹉听觉区域的神经元 前脑在复杂的声音信号中对TF和序列信息进行编码。我将测量单个单位和多个单位 斑雀初级听区Schroeder波对TFS的细胞外选择性 虎皮鹦鹉和我将测量次级听觉区域对顺序变化的不适应程度。在……里面 综上所述，拟议的项目将通过将复杂的听觉感知与 有关TFS和模式处理的行为数据与听觉系统中的神经相关。

Project Summary: In perceiving acoustic communication signals, two of the most important levels at which the central nervous system (CNS) must process sounds are (1) temporal fine structure (TFS) – rapid changes in the frequency and amplitude within the envelope of the speech waveform – and (2) sequential patterns in the structure of acoustic elements. In human language, these abilities are important both for decoding information from speech and in learning to accurately produce words and sentences. While much has been learned about how the auditory cortex in humans computes complex acoustic signals through using non-invasive techniques, it is not known how neurons of the auditory system process the acoustic communication signals at these multiple levels. Vocal learning birds with their complex, learned vocal repertoires and sequentially patterned songs provide very good models for understanding how the brain processes complex acoustic signals. Songbirds, such as zebra finches, and parrots, such as budgerigars, are especially attractive models for asking how the CNS processes complex acoustic signals as the birds can hear TFS at a level that surpasses the capability of humans and other mammals, and the neural mechanisms involved in TFS and sequence processing have been little explored. Moreover, recent experiments have suggested that changes in TFS are much more discriminable to zebra finches than changes in the sequential pattern of song syllables. This is in contrast to humans and budgerigars, for which changes to sequence are very salient. In perception, the coding of neurons in primary and secondary auditory regions for TFS and sequential patterns may help explain why species differ in processing these features. Examining these capacities at the single- and multi-unit level in vocal learning birds could help us, thereby, further understand CNS processing of acoustic communication signals and address central auditory disorders affecting human language. To determine the neural basis for auditory pattern recognition and processing of TFS, I propose the following 2 specific aims: In aim 1, I will compare the discriminability of TFS and sequential patterns in zebra finches, a songbird model, and budgerigars, a parrot model. I will pit these two auditory levels against each other in psychoacoustics testing using Schroeder waveforms, synthetic stimuli that can be manipulated so that only TFS or the sequence of elements is changed, and I will also obtain thresholds in the two species for hearing changes to sequence. In aim 2, I will compare how neurons in auditory regions of the zebra finch and budgerigar forebrains code TFS and sequence information in complex acoustic signals. I will measure single- and multi-unit extracellular selectivity to the TFS of Schroeder waveforms in the primary auditory region of zebra finches and budgerigars and I will measure dishabituation to changes in sequence in a secondary auditory region. In summary, the proposed project will improve scientific knowledge about complex auditory perception by linking behavioral data about TFS and pattern processing with neural correlates in the auditory system.