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Functional organization of morphologically homologous neurons repeated in the adjacent segments of vertebrate hindbrain

脊椎动物后脑相邻节段重复的形态同源神经元的功能组织

基本信息

批准号：
18300134
负责人：
ODA Yoichi
金额：
$ 9.91万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Vertebrate hindbrains are segmented structure. Seven clusters of reticulospinal neurons (RSNs) are periodically arranged along the neuraxis in the hindbrain of zebrafish and goldfish. RSNs sharing a common morphology in adjacent segments are referred to as segmental homologs. In the present study we have investigated the functional organization of a series of segmental homologs, Mauthner (M) cells in the fourth segment (r4) and its homologs in r5 and r6, by examining their activities during escape behavior and mutual connections between them. Confocal calcium imaging of zebrafish RSNs during fast escape behavior in response to water pulse stimulus to head revealed that M-cell initiates acoustically evoked fast escape and its homologs are more involved in tactile evoked escape. M-cell and the homologs show complementary activation during fast escape. The activity relationship is supported by inhibitory connection mediated by inhibitory interneurons from M-cell to the homologs demonstrat … More ed by paired recording of them in goldfish. Acoustically evoked escape behavior appears later than tactile induced escape. We investigated mechanisms underlying acquisition of auditory responsiveness of M cell. Whole-cell recordings from M-cells, exracellular recording of inner ear hair cell (HC) activity and morphological investigations of the auditory afferents from HC to M cells in zebrafish embryos and larvae suggested that functional maturation of inner ear HCs after formation of the auditory afferent circuits is a critical process in the acquisition of auditory inputs by M-cell. Interestingly after acquisition of auditory responsiveness, the M-cell changes their firing pattern in response to stepwise depolarization, from burst as other RSNs exhibit to typical single firing of matured M-cell. Together, the functional differentiation elicited by acquisition of specific sensory input and the interconnection among the homologs may underlie functional organization of segmental homologs to produce adaptive escape behaviors during various environments. Less

脊椎动物的后脑是分节结构。在斑马鱼和金鱼的后脑内，沿神经轴沿着周期性排列着7簇网状脊髓神经元。在相邻片段中共享共同形态的RSN被称为片段同源物。在本研究中，我们调查了一系列的节段同源物，Mauthner（M）细胞在第四节（r4）和它的同源物在r5和r6，通过检查他们的活动在逃避行为和它们之间的相互联系的功能组织。对斑马鱼头部水脉冲刺激引起的快速逃避行为中RSNs的共聚焦钙离子成像显示，M细胞启动听觉诱发的快速逃避，其同系物更多地参与触觉诱发的逃避。M细胞和同源物在快速逃逸过程中表现出互补激活。抑制性中间神经元介导的抑制性连接支持了这种活性关系。 ...更多信息艾德通过在金鱼中配对记录它们。听觉诱发的逃避行为比触觉诱发的逃避行为晚出现。本研究探讨了M细胞听觉反应性获得的机制。对斑马鱼胚胎和幼鱼M细胞的全细胞记录、对内耳毛细胞（HC）活动的细胞外记录以及对HC向M细胞的听觉传入的形态学研究表明，在M细胞获得听觉输入的过程中，内耳毛细胞在听觉传入回路形成后的功能成熟是一个关键过程。有趣的是，在获得听觉反应性后，M细胞改变其放电模式以响应逐步去极化，从其他RSN表现出的爆发到成熟M细胞的典型单次放电。总之，功能分化引起的收购特定的感觉输入和同源物之间的互连可能是功能组织的节段同源物，以产生适应性逃避行为在各种环境。少