Dynamics of odor coding and processing by neural circuits in the olfactory bulb

项目摘要 理解感觉的一个基本步骤是理解大脑中的神经回路 将感觉神经元活动的模式转换为外部世界的强大而有效的表示。 感觉是一个主动的过程，其中感觉信息的检测和初始编码是动态的， 由采样行为调制。了解中枢回路如何处理感觉信息， 主动采样的背景对于理解行为动物中感觉的神经基础是至关重要的。 这个项目的目标是了解哺乳动物嗅球中的神经回路如何转变 在活体内和在主动气味采样或嗅闻的背景下的感觉输入。 首先，我们将研究二尖瓣兴奋性驱动的不同模式的回路水平决定因素 和簇状细胞，重点是感觉输入和肾小球回路在产生这种感觉中的各自作用。 多样性第二，我们将定义刺激是否以及如何表现自己-特别是气味化学和 强度-与MT细胞兴奋驱动的动力学有关，以及这些动力学如何形成 通过嗅探行为。最后，我们将探讨兴奋性输入的动力学和肾小球模式如何影响神经元的功能。 嗅球的输入输出转换。 所提出的实验实施了几种创新的方法来解剖电路功能， 完整的嗅球;这些包括使用谷氨酸的第二代光学报告直接成像 兴奋性信号传导到二尖瓣/簇状细胞上，具有高时间分辨率，谷氨酸和 同时监测突触前输入和从其读出二尖瓣/簇状细胞活动 肾小球，并使用已识别的肾小球与良好表征的反应谱，以设计强大的 模型预测的测试。 该项目的总体影响将是推进对这种关系的机械理解 气味采样的动力学和嗅球中神经活动的动力学之间的关系。 这些发现将为最终理解神经动力学和活动的作用铺平道路。 气味感知中的取样作用。

PROJECT SUMMARY A fundamental step in understanding sensation is understanding how neural circuits in the brain transform patterns of sensory neuron activity into robust and efficient representations of the external world. Sensation is an active process in which the detection and initial encoding of sensory information is dynamically modulated by sampling behavior. Understanding how central circuits process sensory information in the context of active sampling is critical for understanding the neural basis of sensation in the behaving animal. The goals of this project are to understand how neural circuits in the mammalian olfactory bulb transform sensory inputs in vivo and in the context of active odor sampling, or sniffing. First, we will examine circuit-level determinants of the diverse patterns of excitatory drive onto mitral and tufted cells, focusing on the respective roles of sensory inputs and glomerular circuits in generating this diversity. Second, we will define if and how stimulus features themselves – in particular, odorant chemistry and intensity – relate to the dynamics of excitatory drive onto MT cells, as well as how these dynamics are shaped by sniffing behavior. Finally, we will ask how dynamics and glomerular patterns of excitatory input impact the input-output transformation of the olfactory bulb. The proposed experiments implement several innovative approaches to dissecting circuit function in the intact olfactory bulb; these include using second-generation optical reporters of glutamate to directly image excitatory signaling onto mitral/tufted cells with high temporal resolution, dual-color imaging of glutamate and calcium to simultaneously monitor presynaptic inputs and readouts of mitral/tufted cell activity from the same glomerulus, and the use of identified glomeruli with well-characterized response spectra to design powerful tests of model predictions. The overall impact of the project will be to advance a mechanistic understanding of the relationship between the dynamics of odor sampling and the resulting dynamics of neural activity in the olfactory bulb. These findings will pave the way for ultimately understanding the role that neural dynamics and active sampling play in odor perception.