CRCNS: Sparse odor coding in the olfactory bulb

CRCNS：嗅球中的稀疏气味编码

• 批准号: 8837253
• 负责人: ALEXEI KOULAKOV
• 金额: $ 39.58万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8837253
• 关键词: Affect; Animal Behavior; Animals; Area; Award; Brain; Cells; Code; Collaborations; Complex; Data; Dependence; Environment; Equilibrium; Event; Fire - disasters; Food; Frequencies; Gases; Genetic; Goals; Health; Institution; Interneurons; Life; Methods; Minority; Modeling; Neurons; North America; Odors; Olfaction Disorders; Organism; Pattern; Play; Population Heterogeneity; Postdoctoral Fellow; Process; Quality of life; Recruitment Activity; Relative (related person); Research Personnel; Role; Sensory; Sensory Process; Smell Perception; Societies; Staging; Stimulus; System; Testing; Training; combinatorial; experience; flexibility; graduate student; granule cell; information processing; novel; olfactory bulb; olfactory stimulus; optogenetics; programs; research study; response; sensory system; theories; tool; undergraduate student

DESCRIPTION (provided by applicant): Animals acquire information about the environment through their sensory systems. The first sensory stages play a critical role by formatting the representation of this information in an efficient manner that facilitates easy and flexible extraction by downstream areas. Some of the proposed computations in sensory areas of the brain include gain control, decorrelation, orthogonalization, redundancy reduction, and temporal coding. A diverse population of inhibitory interneurons in local brain areas is believed to play a crucial role in these computations. The mammalian olfactory system has multiple features, which make this system uniquely suited to test these ideas: the relative structural simplicity compared to other sensory systems, high relevance of olfaction to animal behavior, availability of modern genetic tools, and the combination of both sensory and state-dependent activity in a single network. Recent efforts of Koulakov and Rinberg groups helped to overcome some obstacles, which slowed down the progress in the field, such as experimental difficulties in controlling olfactory stimuli and insufficient connection between theory and experiment. Capitalizing on the advantages of the system and utilizing recently developed theoretical framework, new optogenetic methods for stimulus control, and multineuron recordings, we propose a collaborative project to test the basic principles of sensory processing in this system. We will investigate an emergence and a role of the temporal code in the representation of odorants in the OB, by studying the role of the interaction of the principal neurons of the olfactory bulb, mitral and tufted cells (MTCs), with the most abundant class of inhibitory interneurons, granule cells (GCs). We will test our recently proposed theory for the MTC-GC network called the Sparse Incomplete Representations (SIR) model. According to the SIR model, GCs form representations of odorants, while MTCs transmit to higher processing centers the errors of these representations. The SIR model predicts that, due to the balance between excitatory odorant-driven inputs from glomeruli and the inhibition from GCs, olfactory code carried by the MTCs becomes combinatorially and temporarily sparse. In the combinatorial form of sparseness, a small fraction of MTCs that receive excitatory inputs yield noticeable responses to odorants that persist through the sniff cycle. In the temporal sparseness, MTCs respond to odorants during a small temporal window within the sniff cycle. Complex temporal patterns of responses will be predicted and tested within this project. Both temporal and combinatorial sparseness are predicted to be dependent on the inputs from cortex, giving the olfactory code an enormous potential flexibility. To test the detailed predictions of the SIR model we propose the following specific aims (SAs): SA1: To investigate diversity of sparse temporal representations of odorants by the MTCs of the OB. Here we will investigate the temporal patterns of responses predicted by the SIR model and compare them with experimental data. We will also study the plasticity of the temporal code carried by the MTCs. SA 2: To investigate the temporal discreteness of sparse representations of odorants by the MTCs of the OB. Here we will study the synchronization of the transient events in MTC firing with ?-frequency oscillations and study the implications for the temporal coding in the OB. SA3: To study the context and state dependence of the sparse representations in the OB. In this Aim we will investigate how the olfactory code carried by the MTCs can be modified dynamically to better fit a particular task. Intellectual merit: Our project will help elucidate the general principles of information processing. We will demonstrate how sensory representations can be dynamically tuned to reflect particular tasks faced by the organism. We will show how networks can adapt to better detect novel features in the environment and disregard familiar ones. We will show how spatial information can be converted into temporal representations by the use of inhibitory interneurons. Broader impacts: The award will provide a unique cross-disciplinary environment for training of young neuroscientists. We expect that two postdoctoral fellows, specializing in theoretical and in experimental approaches, will receive training through this award. Undergraduate students at NYU and CSHL will be involved in the project as summer interns or as senior thesis writers. We will strive to involve minority graduate and undergraduate students, who will be recruited through dedicated programs at each institution. Health implications for the broader society: About 1-2% of people in North America experience a smell disorder. Since our sense of smell helps us enjoy life, may serve as a warning system alerting us of danger, such as spoiled food, fire, or a gas leak, and may be a sign of other health problems, any loss in the sense of smell can negatively affect our quality of life.

描述（由申请人提供）：动物通过其感觉系统获取有关环境的信息。 第一个感官阶段通过以有效的方式格式化该信息的表示来发挥关键作用，从而促进下游区域轻松灵活地提取。 一些提出的大脑感觉区域的计算包括增益控制、去相关、正交化、冗余减少和时间编码。 据信，局部大脑区域中多种抑制性中间神经元发挥着重要作用。 在这些计算中发挥着至关重要的作用。 哺乳动物嗅觉系统具有多种特征，这使得该系统特别适合测试这些想法：与其他感觉系统相比，结构相对简单，嗅觉与动物行为的高度相关性，现代遗传工具的可用性以及感觉和嗅觉的结合单个网络中的状态相关活动。 Koulakov和Rinberg小组最近的努力帮助克服了一些阻碍该领域进展的障碍，例如控制嗅觉刺激的实验困难以及理论与实验之间的联系不足。 利用该系统的优势，并利用最近开发的理论框架、用于刺激控制的新光遗传学方法和多神经元记录，我们提出了一个合作项目来测试该系统中感觉处理的基本原理。 我们将通过研究嗅球、二尖瓣和簇状细胞（MTC）的主要神经元之间相互作用的作用，研究时间编码在 OB 中气味物质表征中的出现和作用。抑制性中间神经元、颗粒细胞（GC）。 我们将测试我们最近提出的 MTC-GC 网络理论，称为稀疏不完整表示 (SIR) 模型。 根据 SIR 模型，GC 形成气味剂的表示，而 MTC 将这些表示的错误传输到更高的处理中心。 SIR 模型预测，由于肾小球的兴奋性气味驱动输入与 GC 的抑制之间的平衡，MTC 携带的嗅觉代码变得组合且暂时稀疏。 在稀疏的组合形式中，一小部分接受兴奋性输入的 MTC 对嗅觉周期中持续存在的气味产生明显的反应。 在时间稀疏的情况下，MTC 在嗅觉周期内的一个小时间窗口内对气味做出反应。 该项目将预测和测试复杂的响应时间模式。 预计时间稀疏性和组合稀疏性都依赖于皮层的输入，从而赋予嗅觉代码巨大的潜在灵活性。 为了测试 SIR 模型的详细预测，我们提出以下具体目标 (SA)： SA1：研究 OB 的 MTC 的气味剂稀疏时间表示的多样性。 在这里，我们将研究 SIR 模型预测的响应的时间模式，并将其与实验数据进行比较。 我们还将研究 MTC 携带的时间代码的可塑性。 SA 2：研究 OB 的 MTC 气味剂稀疏表示的时间离散性。 在这里，我们将研究 MTC 发射中瞬态事件与 频率振荡的同步，并研究对 OB 中时间编码的影响。 SA3：研究 OB 中稀疏表示的上下文和状态依赖性。 在此目标中，我们将研究如何动态修改 MTC 携带的嗅觉代码以更好地适应特定任务。 智力价值：我们的项目将有助于阐明信息处理的一般原理。 我们将演示如何动态调整感官表征以反映有机体面临的特定任务。 我们将展示网络如何适应以更好地检测环境中的新特征并忽略熟悉的特征。 我们将展示如何通过使用抑制性中间神经元将空间信息转换为时间表示。 更广泛的影响：该奖项将为年轻神经科学家的培训提供独特的跨学科环境。 我们预计两名专门从事理论和实验方法的博士后研究员将通过该奖项接受培训。 纽约大学和 CSHL 的本科生将作为暑期实习生或高级论文作者参与该项目。 我们将努力让少数族裔研究生和本科生参与其中，这些学生将通过每个机构的专门项目招募。 对更广泛社会的健康影响：北美大约 1-2% 的人患有嗅觉障碍。 由于我们的嗅觉帮助我们享受生活，可以作为警告系统提醒我们危险，例如变质的食物、火灾或煤气泄漏，并且可能是其他健康问题的征兆，嗅觉的任何损失会对我们的生活质量产生负面影响。