Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia.
Curr Biol. 2021 May 10;31(9):1977-1987.e4. doi: 10.1016/j.cub.2021.01.103. Epub 2021 Mar 2.
Most animals have complex auditory systems that identify salient features of the acoustic landscape to direct appropriate responses. In fish, these features include the volume, frequency, complexity, and temporal structure of acoustic stimuli transmitted through water. Larval fish have simple brains compared to adults but swim freely and depend on sophisticated sensory processing for survival. Zebrafish larvae, an important model for studying brain-wide neural networks, have thus far been found to possess a rudimentary auditory system, sensitive to a narrow range of frequencies and without evident sensitivity to acoustic features that are salient and ethologically important to adult fish. Here, we have combined a novel method for delivering water-borne sounds, a diverse assembly of acoustic stimuli, and whole-brain calcium imaging to describe the responses of individual auditory-responsive neurons across the brains of zebrafish larvae. Our results reveal responses to frequencies ranging from 100 Hz to 4 kHz, with evidence of frequency discrimination from 100 Hz to 2.5 kHz. Frequency-selective neurons are located in numerous regions of the brain, and neurons responsive to the same frequency are spatially grouped in some regions. Using functional clustering, we identified categories of neurons that are selective for a single pure-tone frequency, white noise, the sharp onset of acoustic stimuli, and stimuli involving a gradual crescendo. These results suggest a more nuanced auditory system than has previously been described in larval fish and provide insights into how a young animal's auditory system can both function acutely and serve as the scaffold for a more complex adult system.
大多数动物都有复杂的听觉系统，可以识别声音景观中的显著特征，从而引导做出适当的反应。在鱼类中，这些特征包括通过水传播的声音刺激的音量、频率、复杂性和时间结构。与成年鱼类相比，鱼类幼虫的大脑结构较为简单，但它们可以自由游动，并依赖复杂的感官处理来生存。斑马鱼幼虫是研究全脑神经网络的重要模型，迄今为止，人们发现它们拥有一个基本的听觉系统，对较窄的频率范围敏感，但对成年鱼类中显著且具有生态重要性的声音特征没有明显的敏感性。在这里，我们结合了一种新的输送水载声音的方法、多样化的声音刺激组合以及全脑钙成像，来描述斑马鱼幼虫大脑中单个听觉反应神经元的反应。我们的研究结果显示，这些神经元对 100Hz 到 4kHz 的频率有反应，并且在 100Hz 到 2.5kHz 之间有频率辨别能力。频率选择性神经元分布在大脑的许多区域，对相同频率有反应的神经元在一些区域空间上聚集在一起。通过功能聚类，我们鉴定出了对单一纯音频率、白噪声、声音刺激的急剧起始以及涉及逐渐渐强的刺激有选择性的神经元类别。这些结果表明，与以前在幼鱼中描述的听觉系统相比，斑马鱼幼虫具有更细致的听觉系统，并为年幼动物的听觉系统如何既能急性发挥作用，又能为更复杂的成年系统提供基础提供了一些见解。
