CAREER: Dissecting the whole-brain circuit mechanisms for oxytocinergic control of pain avoidance behavior

摘要：疼痛的经历引发了一系列不同的生理和行为反应，这些反应有助于动物最大限度地减少受伤的可能性，并最大限度地提高其生存几率。因此，描述神经回路对痛苦经历的反应对于更好地理解大脑功能的一个关键方面很重要。为了实现这一目标，该项目将研究斑马鱼幼虫的疼痛处理过程。斑马鱼是一种常见的实验室模型生物，它的大脑与人类的大脑有许多基本特征，同时又足够小，可以以独特的强大方式进行研究和操作。这些特征将使这项工作能够研究产生神经递质催产素的细胞如何在整个大脑的水平上塑造对疼痛的神经表征和行为反应。由于产生催产素的细胞是高度保守的，并且被认为在所有脊椎动物的疼痛处理中都很重要，因此这项工作提供的见解将有助于创建跨物种的神经回路功能模型。因此，这项工作将促进我们对神经系统处理疼痛的基本方式的理解，从而服务于国家利益，这不仅会告诉我们更多关于大脑是如何工作的，总的来说，而且还可能导致对疼痛管理的意想不到的见解。此外，使用一个简单的模式生物将使在这项工作中开发的资源和专业知识能够很容易地应用于高中、大学和研究生水平的各种计划教育活动。虽然脊椎动物下丘脑中的催产素能神经元以其在繁殖、学习和社会行为中的作用而闻名，但越来越多的证据表明，OXT也是疼痛反应的重要调节剂。与其其他功能一样，OXT在疼痛中的作用是综合的，影响多种生理和神经元事件，共同影响行为。虽然之前在哺乳动物中的研究强调了OXT的镇痛和减轻恐惧的作用，但道格拉斯实验室最近发现，在斑马鱼的幼虫中，急性疼痛激活OXT神经元是促进防御性“逃跑”行为的核心事件。OXT在疼痛避免中的作用背后的电路机制，OXT神经元释放的其他神经递质的贡献，以及潜在网络的功能结构都是未知的。目前的建议将使用遗传和光遗传操作结合全脑解剖学、功能成像、电路标记和行为，以确定介导其对疼痛回避影响的OXT神经元的细胞靶点，并表征OXT神经元群体中与行为功能相关的解剖异质性。与此同时，该项目利用其核心专业知识和资源，为高中生开设了一门以斑马鱼为神经科学模型生物的暑期课程，并开设了一门显微镜研究生强化课程。

General AbstractThe experience of pain triggers a host of different physiological and behavioral responses that help an animal minimize the potential for injury and maximize its probability of survival. Describing how neural circuits respond to painful experience is therefore important for better understanding a crucial aspect of brain function. To accomplish this goal, this project will examine pain processing in the larval zebrafish, a common laboratory model organism whose brain shares many essential features with that of humans while being small enough to study and manipulate in uniquely powerful ways. These features will enable this work to investigate how cells that produce the neurotransmitter oxytocin shape the neural representation of and behavioral response to pain, at the level of the entire brain. Because oxytocin-producing cells are highly conserved and thought to be important in pain processing in all vertebrates, the insight provided by this work will help to create models for neural circuit function that generalize across species. The work will therefore serve the national interest by advancing our understanding of the fundamental ways that nervous systems process pain, which will not only tell us more about how brains work, in general, but which could also lead to unexpected insights into pain management. Additionally, the use of a simple model organism will enable resources and expertise developed in this work to be easily applied to a variety of planned educational activities at the high school, college, and graduate levels.Technical AbstractWhile oxytocinergic neurons in the vertebrate hypothalamus are best known for their roles in reproduction, learning, and social behavior, an emerging body of evidence shows that OXT is also an important modulator of the pain response. As with its other functions, OXT's role in pain is integrative, effecting diverse physiological and neuronal events in concert to influence behavior. While previous work in mammals has emphasized the analgesic and fear-attenuating effects of OXT, the Douglass lab has recently discovered that, in the larval zebrafish, activation of OXT neurons by acute pain is a central event in promoting defensive "flight" behaviors. The circuit mechanisms behind OXT's role in pain avoidance, the contribution of other neurotransmitters released by the OXT neurons, and the functional architecture of the underlying networks all remain unknown. The current proposal will use genetic and optogenetic manipulations in combination with whole-brain anatomy, functional imaging, circuit labeling, and behavior, in order to identify the cellular targets of OXT neurons that mediate their effects on pain avoidance and characterize anatomical heterogeneity within the population of OXT neurons with respect to behavioral function. In parallel, the project leverage its core expertise and resources to create a summer course for high school students in the use of zebrafish as a model organism for neuroscience, and an intensive graduate course in microscopy.