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段结构。在斑马鱼和金鱼的后脑中，有七个网状脊髓神经元（RSN）周期性排列，它们在相邻节段中具有共同的形态，被称为节段同源体。一系列节段同源物、第四节段 (r4) 中的 Mauthner (M) 细胞及其 r5 和 r5 中的同源物的功能组织r6，通过检查它们在逃逸行为期间的活动以及斑马鱼 RSN 在快速逃逸行为期间响应头部水脉冲刺激的共聚焦钙成像，发现 M 细胞启动声诱发的快速逃逸，并且其同源物更多地参与其中。触觉诱发逃避。M 细胞和同源物在快速逃避过程中表现出互补激活，这种活动关系得到了 M 细胞与同源物之间的抑制性连接的支持。通过对金鱼的声学诱发逃逸行为进行配对，我们研究了从 M 细胞获得听觉反应的机制，即内耳毛细胞 (HC) 的细胞外记录。）对斑马鱼胚胎和幼虫中从 HC 到 M 细胞的听觉传入的活动和形态学研究表明，听觉传入形成后内耳 HC 的功能成熟电路是 M 细胞获得听觉反应性后获得听觉输入的关键过程，M 细胞响应逐步去极化而改变其放电模式，从其他 RSN 表现出的突发到成熟 M 的典型单次放电。总之，通过获取特定的感觉输入和同系物之间的互连引起的功能分化可能是分段同系物的功能组织的基础，以在各种环境下产生适应性逃避行为。