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(申请人提供)：动物通过它们的感官系统获取有关环境的信息。第一个感觉阶段发挥了关键作用，以一种有效的方式格式化了这种信息的表示，便于下游地区容易和灵活地提取。大脑感觉区域的一些拟议计算包括增益控制、去相关、正交化、减少冗余和时间编码。据信，局部脑区的不同数量的抑制性中间神经元在 在这些计算中起着至关重要的作用。哺乳动物的嗅觉系统具有多种特征，这使得这个系统非常适合测试这些想法：与其他感觉系统相比，结构相对简单，嗅觉与动物行为高度相关，现代遗传工具的可用性，以及感觉和状态依赖活动在单一网络中的组合。Koulakov和Rinberg团队最近的努力帮助克服了一些障碍，这些障碍减缓了该领域的进展，例如控制嗅觉刺激的实验困难以及理论和实验之间的联系不足。利用该系统的优势，利用最新发展的理论框架、新的光遗传刺激控制方法和多神经元记录，我们提出了一个合作项目，以测试该系统中感觉加工的基本原理。 我们将通过研究嗅球、二尖瓣和簇状细胞(MTCs)的主要神经元与最丰富的抑制性中间神经元颗粒细胞(GCs)之间的相互作用，来研究OB区气味表征中时间代码的出现和作用。我们将测试我们最近提出的用于MTC-GC网络的理论，称为稀疏不完全表示(SIR)模型。根据SIR模型，GC形成气味的表示，而MTC将这些表示的误差传递到更高的处理中心。SIR模型预测，由于来自肾小球的兴奋性气味驱动的输入和来自GC的抑制之间的平衡，MTCs携带的嗅觉编码变得组合和暂时稀疏。在稀疏性的组合形式中，一小部分接受兴奋性输入的MTC对气味产生明显的反应，这些气味在嗅觉循环中持续存在。在时间稀疏性中，MTC在嗅觉周期内的一个小时间窗口内对气味做出反应。将在该项目中预测和测试复杂的响应时间模式。时间稀疏性和组合稀疏性都被预测依赖于来自大脑皮层的输入，这给嗅觉代码带来了巨大的潜在灵活性。为了测试SIR模型的详细预测，我们提出了以下具体目标(SA)：SA1：调查OB的MTC对气味稀疏时间表征的多样性。在这里，我们将研究SIR模型预测的响应的时间模式，并将它们与实验数据进行比较。我们还将研究MTC所携带的时间码的可塑性。SA 2：研究OB的MTC对气味稀疏表示的时间离散性。在这里，我们将研究具有？-频率振荡的MTC发射中的瞬时事件的同步，并研究其对OB中的时间编码的影响。SA3：研究OB中稀疏表示的上下文和状态依赖关系。在这个目标中，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。 智力优势：我们的项目将有助于阐明信息处理的一般原则。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一个独特的跨学科环境。我们预计，两名博士后研究员将通过这一奖项接受培训，他们专门从事理论和实验方法。纽约大学和CSHL的本科生将以暑期实习生或高级论文作者的身份参与该项目。我们将努力让少数族裔研究生和本科生参与进来，他们将通过每个院校的专门项目招收。对更广泛社会的健康影响：在北美，大约1%-2%的人经历了气味障碍。因为我们的嗅觉可以帮助我们享受生活，可以作为一个警告系统，提醒我们有危险，如变质的食物、火灾或煤气泄漏，也可能是其他健康问题的迹象，嗅觉的任何丧失都会对我们的生活质量产生负面影响。