Circuits for spontaneous behavior and phototaxis in a simple model chordate

简单脊索动物模型中自发行为和趋光性的电路

• 批准号: 10446697
• 负责人: William Smith
• 金额: $ 66.48万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA BARBARA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-15 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10446697
• 关键词: 3-Dimensional; Ablation; Address; Anatomy; Animals; Anterior; Automobile Driving; Behavior; Brain; Brain region; Cells; Chordata; Complement; Complex; Cues; Data; Development; Embryo; Environment; Frequencies; Human; Individual; Interneurons; Larva; Lasers; Lead; Light; Lighting; Link; Location; Modeling; Movement; Names; Nervous system structure; Neurons; Pattern; Periodicity; Pharmacology Study; Phase; Photoreceptors; Picrotoxin; Positioning Attribute; Property; Regulator Genes; Regulatory Element; Research Personnel; Role; Source; Swimming; Synapses; Tail; Testing; Trees; Urochordata; Vertebrates; Vesicle; base; behavioral outcome; cholinergic; cholinergic neuron; connectome; experimental study; falls; gamma-Aminobutyric Acid; inhibitor; insight; large datasets; mutant; neural circuit; neural model; optogenetics; time interval; tool

This proposal will investigate neural circuits driving negative phototaxis in an emerging model for neural circuit analysis: larvae of the primitive chordate Ciona. Ciona larvae have a number of features that make them ideally suited for this project. They are small and transparent, and have only 177 CNS neurons. Moreover, putative circuits for phototaxis have been identified from the Ciona connectome. Negative phototaxis in Ciona larvae consists of two phases. First, the larvae perform short orienting swims in which they attempt to discern the direction of ambient lighting by moving their bodies. Second, if the larva detects a change in light falling on their photoreceptors as they turn away from the light source, a sustained negative phototactic swim results. However, many orienting swims terminate without a sustained swim. This proposal will examine two aspects of phototaxis: 1) how neural circuits regulate the frequency of orienting swims; and 2) how orienting and sustained swims are linked at the circuit level. Ciona larvae show a wide distribution in the time intervals between short orienting swims. However, analysis of a large dataset of swim interval times points to underlying oscillations governing spontaneous swims frequency, with the dominant period being once every two seconds (O.5 Hz). In preliminary studies we have identified a VGAT-positive neuron that oscillates with a frequency of 0.5 Hz in a region of Ciona CNS called the anterior brain vesicle. We have named the oscillating neuron the anterior brain vesicle oscillator (aBVO). Moreover, mutant and pharmacological studies both point to the aBVO as a likely regulator of spontaneous swim frequency. Proposed experiments in Specific Aim 1 will target the aBVO neuron using optogenetic tools and laser ablation, and then assess the behavioral outcomes. Specific Aim 2 will address the second question: what is the circuit link between short spontaneous orienting and sustained phototactic swims? Our preliminary studies recording GCaMP activity in VACHT-positive neurons suggest a plausible and testable circuit model. We observed that short spontaneous tail movements in larvae were accompanied by Ca2+ transients in the same VACHT-positive interneurons that are the primary targets of the photoreceptors - a neuron class called photoreceptor relay neurons (prRNs). Moreover, the connectome allowed us to identify likely candidate neurons corresponding to the aBVO, based on their 3D locations and connectivities, and the major synaptic targets of these candidate neurons are also the prRNs. Thus, we hypothesize that short orienting swims are initiated in the same circuit as the sustained phototactic swims, and it is the presence or absence of input from the photoreceptors that determines if a sustained swim is initiated. Experiments in Specific Aim 2 will test this hypothesis by targeting the prRNs to determine if they are necessary for the initiation of orienting swims. We also hypothesize that in the absence of aBVO inhibition the prRNs would oscillate. We will test this hypothesis by examining a mutant line that lacks the aBV region of the CNS.

该提案将研究在神经回路的新兴模型中驱动负面光的神经回路 分析：原始脊全ciona的幼虫。西奥纳幼虫具有许多使它们的功能 非常适合该项目。它们很小且透明，只有177个CNS神经元。而且， 已经从Ciona Connectome确定了用于光的推定电路。 ciona中的负光 幼虫由两个阶段组成。首先，幼虫进行简短的游泳，他们试图辨别 环境照明通过移动身体的方向。其次，如果幼虫检测到光的变化 当它们远离光源时，它们的光感受器是持续的阴性游泳结果。 但是，许多方向游泳在没有持续游泳的情况下终止。该建议将研究 光疗：1）神经回路如何调节定向游泳的频率； 2）如何定位和 持续的游泳在电路级别连接。 ciona幼虫在时间间隔内显示出广泛的分布 在短期游泳之间。但是，分析大型游泳间隔时间数据集的基础点 振荡自发游泳频率，主要时期每两秒钟一次 （O.5 Hz）。在初步研究中，我们已经确定了一个VGAT阳性神经元，该神经元以频率为oscill 在CNS区域中，0.5 Hz称为前脑囊泡。我们命名了振荡的神经元 前脑囊泡振荡器（ABVO）。此外，突变体和药理学研究都指向ABVO 作为自发游泳频率的可能调节器。特定目标1中的拟议实验将针对 使用光遗传学工具和激光消融，然后评估行为结果。具体的 AIM 2将解决第二个问题：短自发方向和 持续的照相游泳？我们的初步研究记录了VACHT阳性神经元中GCAMP活性 建议一个合理且可测试的电路模型。我们观察到幼虫中的短自发性尾部运动 伴随着同一VACHT阳性中间神经元中的Ca2+瞬变，这是 感光体 - 一种称为感光体中继神经元（PRRNS）的神经元类。而且，连接组 允许我们根据其3D位置确定与ABVO相对应的候选神经元的 连接性以及这些候选神经元的主要突触靶标也是PRRN。因此，我们 假设在与持续的照相游泳相同的电路中启动短时游泳，并且 来自光感受器的存在或不存在输入，决定是否启动了持续的游泳。 特定目标2中的实验将通过靶向PRRN来确定是否是 启动定向游泳所必需的。我们还假设，在没有ABVO抑制的情况下 PRRN会振荡。我们将通过检查缺乏缺乏ABV区域的突变线来检验这一假设 CNS。

项目成果

A single oscillating proto-hypothalamic neuron gates taxis behavior in the primitive chordate Ciona.

单个振荡的原下丘脑神经元控制着原始脊索动物海鞘的滑行行为。

• DOI: 10.1101/2023.04.24.538092
• 发表时间: 2023
• 期刊: bioRxiv : the preprint server for biology
• 作者: Chung,Janeva;Newman-Smith,Erin;Kourakis,MatthewJ;Miao,Yishen;Borba,Cezar;Medina,Juan;Laurent,Tao;Gallean,Benjamin;Faure,Emmanuel;Smith,WilliamC
• 通讯作者: Smith,WilliamC