Hsieh Jui-Yi, Ulrich Brittany, Issa Fadi A, Wan Jijun, Papazian Diane M
Department of Physiology, David Geffen School of Medicine at University of California Los Angeles Los Angeles, CA, USA ; Interdepartmental Ph.D. Program in Molecular, Cellular, and Integrative Physiology, David Geffen School of Medicine at University of California Los Angeles Los Angeles, CA, USA.
Department of Physiology, David Geffen School of Medicine at University of California Los Angeles Los Angeles, CA, USA.
Front Neural Circuits. 2014 Dec 19;8:147. doi: 10.3389/fncir.2014.00147. eCollection 2014.
The zebrafish has significant advantages for studying the morphological development of the brain. However, little is known about the functional development of the zebrafish brain. We used patch clamp electrophysiology in live animals to investigate the emergence of excitability in cerebellar Purkinje cells, functional maturation of the cerebellar circuit, and establishment of sensory input to the cerebellum. Purkinje cells are born at 3 days post-fertilization (dpf). By 4 dpf, Purkinje cells spontaneously fired action potentials in an irregular pattern. By 5 dpf, the frequency and regularity of tonic firing had increased significantly and most cells fired complex spikes in response to climbing fiber activation. Our data suggest that, as in mammals, Purkinje cells are initially innervated by multiple climbing fibers that are winnowed to a single input. To probe the development of functional sensory input to the cerebellum, we investigated the response of Purkinje cells to a visual stimulus consisting of a rapid change in light intensity. At 4 dpf, sudden darkness increased the rate of tonic firing, suggesting that afferent pathways carrying visual information are already active by this stage. By 5 dpf, visual stimuli also activated climbing fibers, increasing the frequency of complex spiking. Our results indicate that the electrical properties of zebrafish and mammalian Purkinje cells are highly conserved and suggest that the same ion channels, Nav1.6 and Kv3.3, underlie spontaneous pacemaking activity. Interestingly, functional development of the cerebellum is temporally correlated with the emergence of complex, visually-guided behaviors such as prey capture. Because of the rapid formation of an electrically-active cerebellum, optical transparency, and ease of genetic manipulation, the zebrafish has great potential for functionally mapping cerebellar afferent and efferent pathways and for investigating cerebellar control of motor behavior.
斑马鱼在研究大脑形态发育方面具有显著优势。然而，人们对斑马鱼大脑的功能发育了解甚少。我们利用活体动物的膜片钳电生理学技术，研究小脑浦肯野细胞兴奋性的出现、小脑回路的功能成熟以及小脑感觉输入的建立。浦肯野细胞在受精后3天（dpf）产生。到4 dpf时，浦肯野细胞以不规则模式自发发放动作电位。到5 dpf时，紧张性发放的频率和规律性显著增加，并且大多数细胞在攀爬纤维激活时发放复合动作电位。我们的数据表明，与哺乳动物一样，浦肯野细胞最初由多条攀爬纤维支配，随后逐渐筛选为单一输入。为了探究小脑功能性感觉输入的发育情况，我们研究了浦肯野细胞对由光强度快速变化组成的视觉刺激的反应。在4 dpf时，突然变暗增加了紧张性发放的速率，这表明携带视觉信息的传入通路在这个阶段已经活跃。到5 dpf时，视觉刺激也激活了攀爬纤维，增加了复合动作电位的频率。我们的结果表明，斑马鱼和哺乳动物浦肯野细胞的电特性高度保守，并表明相同的离子通道Nav1.6和Kv3.3是自发起搏活动的基础。有趣的是，小脑的功能发育在时间上与复杂的、视觉引导行为（如捕食）的出现相关。由于电活性小脑的快速形成、光学透明性以及易于进行基因操作，斑马鱼在功能绘制小脑传入和传出通路以及研究小脑对运动行为的控制方面具有巨大潜力。
