CRCNS: Sparse odor coding in the olfactory bulb

CRCNS：嗅球中的稀疏气味编码

• 批准号: 9066624
• 负责人: ALEXEI KOULAKOV
• 金额: $ 36.76万
• 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/9066624
• 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; Internships; Life; Methods; Minority Graduate Student; Modeling; Neurons; North America; Odors; Olfaction Disorders; Olfactory Pathways; Organism; Pattern; Play; Population Heterogeneity; Postdoctoral Fellow; Process; Quality of life; Recruitment Activity; Role; Sensory; Sensory Process; Smell Perception; Societies; Staging; Stimulus; System; Testing; Training; combinatorial; experience; flexibility; granule cell; information processing; minority undergraduate; novel; olfactory bulb; olfactory stimulus; optogenetics; predicting response; 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 γ-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。 第一感觉阶段通过以有效的方式格式化该信息的表示，从而促进下游区域的容易和灵活的提取，从而发挥关键作用。 在大脑的感觉区域中提出的一些计算包括增益控制、去相关、正交化、冗余减少和时间编码。 据信，局部脑区的抑制性中间神经元的多样性群体发挥着重要作用。 在这些计算中起着关键作用。 哺乳动物的嗅觉系统具有多种特征，这使得该系统特别适合于测试这些想法：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，以及感觉和状态依赖活动在单个网络中的组合。 Koulakov和Rinberg小组最近的努力有助于克服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，新的光遗传学方法的刺激控制，和多神经元记录，我们提出了一个合作项目，以测试在这个系统中的感觉处理的基本原则。 我们将调查的出现和作用的时间代码中的代表性的气味在OB，通过研究的作用的主要神经元的嗅球，二尖瓣和簇状细胞（MTCs）的相互作用，与最丰富的类的抑制性中间神经元，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递到更高的处理中心。 SIR模型预测，由于兴奋性气味驱动的输入肾小球和抑制GC之间的平衡，嗅觉代码进行的MTCs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，这些反应持续通过嗅闻周期。 在时间稀疏性中，MTCs在嗅闻周期内的小时间窗口期间对气味物作出响应。 复杂的时间模式的反应将在这个项目中进行预测和测试。 时间和组合稀疏性都依赖于来自皮层的输入，这给嗅觉编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）：SA 1：调查的多样性稀疏的时间表示的气味的的MTC的OB。 在这里，我们将调查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MTCs携带的时间代码的可塑性。 SA 2：研究OB的MTC对气味的稀疏表示的时间离散性。 在这里，我们将研究MTC发射中的瞬态事件与γ频率振荡的同步，并研究OB中时间编码的影响。 SA 3：研究OB中稀疏表示的上下文和状态依赖性。 在这个目标中，我们将研究如何进行的MTCs的嗅觉代码可以动态修改，以更好地适应特定的任务。 智力价值：我们的项目将有助于阐明信息处理的一般原则。 我们将展示如何感官表征可以动态调整，以反映所面临的有机体的特定任务。 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征。 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，专门从事理论和实验方法，将通过这个奖项接受培训。 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。 我们将努力让少数民族研究生和本科生参与进来，他们将通过每所机构的专门课程招募。 对更广泛社会的健康影响：北美约有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，可以作为一个警告系统提醒我们危险，如变质的食物，火灾或煤气泄漏，并可能是其他健康问题的迹象，嗅觉的任何损失都会对我们的生活质量产生负面影响。