Molecular and Cellular Mechanisms of a Neuronal Network that Regulates Olfactory

描述(由申请人提供)：我们有兴趣了解个体如何通过嗅觉与环境交流，尤其是嗅觉反应是如何通过经验和环境线索塑造和改变的。为此，我们使用遗传模型生物秀丽线虫和一种新形式的嗅觉可塑性在这个动物模型中提出以下问题：支持嗅觉学习的神经元回路的功能组织是什么？经验是如何产生调节线索来改变嗅觉的？嗅觉回路的固有特性是如何随着经验的变化而产生嗅觉学习的？我们之前已经证明，线虫在摄入病原体后，会学习避免病原体的气味。来自一对5-羟色胺能神经元ADF和嗅觉回路的5-羟色胺信号对于指导这一学习过程是必不可少的。感染的生理应激通过CaMKII和GQ途径增强ADF 5-羟色胺信号；增强的信号通过几个中间神经元中的5-羟色胺门控通道促进学习。这种学习需要两对感觉神经元下游的嗅觉神经回路。我们假设，增强的5-羟色胺信号调节嗅觉回路的特性，导致嗅觉的变化。为了验证这一假说并描述这一学习过程的分子和细胞机制，我们将首先使用遗传消融和激光手术来绘制支持嗅觉学习的神经回路，并定义这个网络的神经元组件。然后，我们将使用钙成像来检查幼年动物和习得动物嗅觉回路的神经元特性。最后，我们将使用分子遗传学和生化工具来表征训练经验如何通过CaMKII和GQ信号通路产生神经调节性5-羟色胺信号。

DESCRIPTION (provided by applicant): We are interested to understand how individuals communicate with environment by olfaction and, particularly, how olfactory responses are shaped and modified by experience and environmental cues. To this end, we use a genetic model organism Caenorhabditis elegans and a new form of olfactory plasticity in this animal model to ask the following questions: What is the functional organization of the neuronal circuit underlying olfactory learning? How does experience generate modulatory cues to modify olfaction? How does the intrinsic property of the olfactory circuitry change in response to experience to generate olfactory learning? We previously showed that C. elegans learns to avoid the smell of pathogenic bacteria after ingestion of the pathogens. Serotonin signaling from a pair of serotonergic neurons ADF and an olfactory circuit are essential to direct this learning process. The physiological stress of infection enhances ADF serotonin signals through CaMKII and a Gq pathway; and the strengthened signaling promotes learning through a serotonin-gated channel in several interneurons. An olfactory neural circuit downstream of two pairs of sensory neurons is required for this learning to occur. We hypothesize that the enhanced serotonin signaling modulates the properties of the olfactory circuit, resulting in a change in olfaction. To test this hypothesis and characterize the molecular and cellular mechanisms of this learning process, we will first use genetic ablation and laser surgery to map the neural circuit underlying the olfactory learning and define the neuronal components of this network. Then we will use calcium imaging to examine the neuronal properties of the olfactory circuit in both na¿ve and learned animals. And finally we will use molecular genetics and biochemical tools to characterize how the training experience generates a neuromodulatory serotonin signaling through CaMKII and a Gq signaling pathway.