Initial Stages of Olfactory Information Processing

项目概要/摘要 该项目的长期目标是揭示复杂气味编码的机制， 特别关注嗅觉信息处理的初始阶段。研究设计利用了 黑腹果蝇的解剖简单性和强大的遗传工具包，它允许系统的 嗅觉回路的分子遗传学分析，以及嗅觉回路的深入生理和行为分析， 嗅觉功能这些结果可能对控制疾病的昆虫媒介具有重要意义。 该项目的重点是ephaptic相互作用，一种新颖的，非突触形式的嗅觉回路通信， 这发生在同一种昆虫中的任何两组嗅觉受体神经元（ORN）之间 感觉毛（sensillum）。尽管它的普遍性，如何ephaptic通信调节嗅觉功能， 人们对行为知之甚少。我们最近首次描述了肝纤维化的重要性， 昆虫嗅觉抑制。在目前的研究中，我们将首先集中在定义的重要性， 激发将进行系统的功能检查，以确定视乳头兴奋的强度 在分组的ORN之间（目标1）。分组的ORN的各自的电紧张性质也将被描述。 目标2（Aim 2）将对来自两种细胞的一对ORN之间的ephaptic相互作用的强度进行量化。 方向，以期测试的假设，ephaptic相互作用是不对称的整个感器 类型此外，还将用连续块面电子显微镜描述成组的ORN的超微结构。 显微镜（SBEM）和3D重建成像技术（Aim 3）。本目标旨在确定 生物物理因素的基础上不对称ephaptic相互作用感器。的形态特征 将分析识别的ORN，例如树突口径、树突分支的数量以及索马大小 并在相邻的ORN之间进行比较。假设一对中身体较大的ORN发挥 将测试在其相邻物上的更强的ephaptic相互作用。这一目标也可能导致关键的技术 突破，以扩大应用SBEM在照亮3D超微结构的任何确定的细胞， 不同的组织最后，气味引导行为中的ephaptic相互作用的功能重要性将是 已确定（目标4）。具体地说，我们将扩展我们的行为分析，并确定ephaptic抑制的作用， 感器中的求偶行为，感器中的ORN对信息素线索有反应。我们还将表演 第一个测试的功能重要性，ephaptic兴奋之间的另一个ORN对，介导 对食物气味的行为反应 拟议的研究将确定一种新形式的功能重要性和生物物理学原理， 嗅觉回路相互作用机制这些发现有可能彻底改变我们对 昆虫的嗅觉信息处理，并可能揭示控制化学感觉的一般原则 动物王国中的行为。

PROJECT SUMMARY/ABSTRACT The long-term goal of this project is to reveal the mechanisms by which complex odors are encoded, with a special focus on the initial stages of olfactory information processing. The research design takes advantage of the anatomical simplicity and powerful genetic toolkit of Drosophila melanogaster, which allows systematic molecular genetic analysis of olfactory circuits as well as in-depth physiological and behavioral analysis of olfactory function. The results may have major implications for the control of insect vectors of disease. The project focuses on ephaptic interactions, a novel, non-synaptic form of olfactory circuit communication, which take place between any two grouped olfactory receptor neurons (ORNs) housed in the same insect sensory hair (sensillum). Despite its ubiquity, how ephaptic communication regulates olfactory function and behavior is poorly understood. We recently provided the first description of the importance of ephaptic inhibition in insect olfaction. In the current study, we will first focus on defining the importance of ephaptic excitation. A systematic, functional survey will be performed to define the strength of ephaptic excitation between grouped ORNs (Aim 1). The respective electrotonic properties of grouped ORNs will also be determined (Aim 2). The strength of ephaptic interactions will be quantified between a pair of ORNs from both directions with a view to testing the hypothesis that ephaptic interactions are asymmetric across sensillum types. Furthermore, the ultrastructure of grouped ORNs will be described using serial block-face electron microscopy (SBEM) and 3D reconstruction imaging technologies (Aim 3). This Aim is designed to identify the biophysical factors that underlie asymmetric ephaptic interactions in a sensillum. Morphological features of an identified ORN, such as dendritic caliber, number of dendritic branches, as well as soma size, will be analyzed and compared between neighboring ORNs. The hypothesis that the physically larger ORN in a pair exerts stronger ephaptic interactions upon its neighbor will be tested. This Aim could also lead to critical technical breakthroughs to broaden the application of SBEM in illuminating the 3D ultrastructure of any identified cell in diverse tissues. Lastly, the functional importance of ephaptic interactions in odor-guided behavior will be determined (Aim 4). Specifically, we will extend our behavioral assay and define the role of ephaptic inhibition on courtship behavior in sensillum which houses ORNs responsive to pheromone cues. We will also perform the first test of the functional importance of ephaptic excitation between another ORN pair that mediates behavioral responses to food odors. The proposed research will determine the functional importance and biophysical principles of a novel form of olfactory circuit interaction mechanism. These findings have the potential to revolutionize our understanding of olfactory information processing in insects, and may reveal general principles that govern chemosensory behavior throughout the animal kingdom.