Animals adapt their behaviors to their ever-changing needs. Internal states, such as hunger, fear, stress, and arousal are important behavioral modulators by controlling the way an organism perceives sensory stimuli and reacts to them. The translucent zebrafish larva is an ideal model organism for studying neuronal circuits regulating brain states, owning to the possibility of easy imaging and manipulating activity of genetically identified neurons while the animal performs stereotyped and well-characterized behaviors. The main neuromodulatory circuits present in mammals can also be found in the larval zebrafish brain, with the advantage that they contain small numbers of neurons. Importantly, imaging and behavioral techniques can be combined with methods for generating targeted genetic modifications to reveal the molecular underpinnings mediating the functions of such circuits. In this review we discuss how studying the larval zebrafish brain has contributed to advance our understanding of circuits and molecular mechanisms regulating neuromodulation and behavioral flexibility.

中文翻译：

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斑马鱼幼虫的神经调节和行为灵活性：从神经递质到回路

动物会根据不断变化的需求调整自己的行为。内部状态，例如饥饿、恐惧、压力和唤醒，是重要的行为调节剂，通过控制有机体感知感官刺激并对其作出反应的方式。半透明的斑马鱼幼虫是研究调节大脑状态的神经元回路的理想模型生物，因为在动物执行刻板和良好表征的行为时，可以轻松成像和操纵遗传识别神经元的活动。哺乳动物中存在的主要神经调节回路也可以在斑马鱼幼虫的大脑中找到，其优点是它们包含少量神经元。重要的，成像和行为技术可以与产生靶向遗传修饰的方法相结合，以揭示介导此类回路功能的分子基础。在这篇综述中，我们讨论了研究斑马鱼幼虫大脑如何促进我们对调节神经调节和行为灵活性的电路和分子机制的理解。