Sniffing and optical imaging of olfactory bulb responses

描述（由申请人提供）：本项目的目标是了解嗅觉受体神经元群体在其输入到嗅球的水平上的气味表征如何通过清醒大鼠的嗅探进行修改。虽然嗅球和嗅闻行为的群体反应已经在一定程度上被分离出来，并且已经清楚嗅闻可能对气味编码产生重大影响，但嗅闻实际上如何影响嗅觉系统中的气味编码是完全未知的。气味信息从空间上粗略组织的嗅上皮到空间上高度组织的嗅球的转换，允许高度特异性的嗅觉受体神经元会聚到肾小球上，是这个编码过程中的关键步骤。很明显，气流可以调节气味吸附到嗅上皮的位置，而且很明显，受体神经元的空间组织绝不是随机的。嗅球的输入，就像一个窗口的嗅觉受体剧目的气味，因此可能会受到影响的嗅探。如果是这样的话，这无疑对高阶处理也有重大影响。事实上，几个重要的假设依赖于嗅探是不变的假设。本研究将集中在嗅觉通路的第一级气味的编码和处理的信息的气味的嗅觉嗅觉刺激剂的影响，通过选择性成像活动在嗅觉受体神经元末梢，而大鼠正在执行嗅觉辨别任务和嗅觉活动的测量。具体而言，本研究将：1）确定嗅闻在多大程度上调节嗅球中的神经气味图; 2）确定响应于较低气味剂浓度的增强的嗅闻现象是否导致到嗅球的输入气味图的浓度不变性。总之，这些实验将构成一个重要的一步，了解气味质量编码在特定水平的嗅觉通路是如何受到影响的无处不在的和自然的行为嗅大鼠。了解嗅觉系统的基本功能可能会改善神经系统疾病的诊断和治疗。

DESCRIPTION (provided by applicant): The goal of this project is to understand how odorant representations by populations of olfactory receptor neurons at the level of their input to the olfactory bulb are modified by sniffing in awake rats. While population responses of the olfactory bulb and sniffing behavior have been explored to some degree in separation, and it has become clear that sniffing could have a major impact on odorant encoding, it is entirely unknown how sniffing actually affects odor encoding in the olfactory system. The transformation of odorant information from the spatially roughly organized olfactory epithelium to the spatially highly organized olfactory bulb, allowed by highly specific convergence of olfactory receptor neurons onto glomeruli, is a critical step in this encoding process. It is clear that airflow can modulate where odorants sorb to the olfactory epithelium, and it is clear that the spatial organization of receptor neurons is by no means random. The input of the olfactory bulb, which acts like a window on the olfactory receptor repertoire of odorants, is hence likely to be affected by sniffing. If so, this undoubtedly has major affects on higher order processing as well. Indeed, several important hypotheses rely on the assumption that sniffing is invariable. This study will focus on the impact of sniffing of odorants on the coding and processing of information about odors at this first level of the olfactory pathway by selectively imaging activity in olfactory receptor neuron terminals while rats are performing an olfactory discrimination task and sniffing activity is measured. Specifically, this study will: 1) determine to what extent sniffing modulates the neural odormaps in the olfactory bulb; 2) determine whether the phenomenon of enhanced sniffing in response to lower odorant concentrations leads to concentration-invariance of input odormaps to the bulb. Together, these experiments will constitute a significant step towards understanding how odor quality - encoding at a specific level of the olfactory pathway is affected by the ubiquitous and natural behavior of sniffing in rats. Understanding the basic functions of the olfactory system can potentially lead to improved diagnosis and treatment of diseases of the nervous system.