Neuronal Mechanisms of Auditory Stream Segregation in an Insect

利用声音信号感知环境的动物依赖于它们在大量不相关的声音中发现相关声音信号的能力。这种听觉场景分析的早期步骤是将到达耳朵的声音混合感知分组为声源的连贯表示（=听觉流分离）。这个过程在许多脊椎动物中都有描述。尽管听觉场景分析已经在各种系统中得到了深入的研究，但对听觉场景分析背后的神经元过程的理解仍然有限，并且听觉流分离的可测试的神经元模型目前还不可用。最近，在一个无脊椎动物系统中，听觉流分离被描述：一个蝈蝈儿听觉中间神经元（TN-1）从雄性交流叫声的背景中分离出蝙蝠的回声定位叫声信息。本项目研究了katydids （insect, tetigoniidae）中TN-1分离听觉流的神经机制。最终，我们的目标是建立一个神经元模型，在离子通道、细胞和网络的水平上研究听流分离。项目的第一部分确定了该系统中听觉流分离的行为背景的重要性。对接受和不接受雄性鸣叫的雌性之间的隔离行为进行了比较。研究的第二部分利用细胞内TN-1树突的记录，确定了抑制TN-1对雄性鸣叫反应的机制。在不同的实验条件下，测量膜电导的变化以响应适应刺激。研究的第三部分通过测量膜电导和钙或钠成像来测试导致对雄性鸣叫的抑制反应的过程是否只发生在树突的有限区域。本项目为听觉场景分析和感官处理的研究建立了一个新的模型体系和假设。因此，这可能是对神经生物学的重要贡献。该项目包括从研究到教育的直接转移：行为测试和细胞外记录的实验设置经过修改，以适合本科或高中水平的课堂教学。该项目包括培养几名本科生和研究生以及一名博士后。这个项目是密苏里大学建立计算神经科学研究生和本科生培训的更大努力的一部分。

Animals that use acoustic signals to perceive their environment depend on their ability to detect relevant sound signals among an abundance of irrelevant sounds. An early step in this analysis of the auditory scene is the perceptual grouping of the acoustic mixture reaching the ear into coherent representations of sound sources (= Auditory Stream Segregation). This process has been described in a variety of vertebrates. Although auditory scene analysis has been intensively studied in a variety of systems, the understanding of the neuronal processes underlying auditory scene analysis remains limited, and testable neuronal models of auditory stream segregation are currently not available. Recently, auditory stream segregation has been described in one invertebrate system: a katydid auditory interneuron (TN-1) segregates information about bat echolocation cries from a background of male communication calls. This project investigates the neuronal mechanisms underlying auditory stream segregation by TN-1 in katydids (Insecta, Tettigoniidae). Ultimately, the goal is to establish a neuron model to study auditory stream segregation at the levels of ion-channels, cells and networks. The first part of the project determines the importance of the behavioral context for auditory stream segregation in this system. The segregation performance is compared behaviorally between females that are either receptive or non-receptive to male calls. The second part of the study identifies the mechanisms underlying the suppression of TN-1 responses to male calls, using intracellular recordings from TN-1 dendrites. Changes in membrane conductance are measured in response to adapting stimuli under various experimental situations. The third part of the study tests whether the processes leading to the suppression of responses to male calls occur only in restricted areas of the dendrite, using measurements of membrane conductance and calcium or sodium imaging. This project establishes a new model system and a novel hypothesis to the study of auditory scene analysis and sensory processing in general. It is therefore likely to be an important contribution to neurobiology. This project includes a direct transfer from research to education: the experimental setup for behavioral tests and extracellular recordings is modified to be suitable for classroom teaching at undergraduate or high school level. This project includes training of several undergraduate and graduate students as well as a postdoctoral associate. This project is part of a larger effort at the University of Missouri to establish graduate and undergraduate training in computational neuroscience.