Characterizing odor motion detection in flies

许多动物依靠它们导航到空气中气味羽流来源的能力生存。研究断代 一个世纪以前的研究表明，昆虫结合了机械感觉和嗅觉线索来导航，涌动着 当检测到气味时逆风，但当失去信号时则顺风或顺风。他们还使用双边 从它们的两个触角获得的信息转向更高的气味浓度。我们最近发现，在 除了风向和气味梯度外，果蝇还可以检测气味的运动方向，而不依赖于 风。利用光遗传学将气味信号从风中分离出来，我们发现苍蝇通过 它们两个触角之间气味信号的时间相关性，表明与运动检测相似 在视觉上。操纵虚拟气味信号中的时空相关性表明苍蝇确实利用了 在气味羽流导航时的气味运动。 果蝇能“闻”到气味运动的这一发现表明，在大脑的双侧感觉中， 嗅觉，并为该领域提出了以下问题：1)气味运动是如何进行的--这是以前未被认识到的 嗅觉定向线索-与其他定向线索相结合来驱动嗅觉导航？2)什么是 气味运动检测器的输入，以及气味价态如何调节对气味运动的行为反应？ 什么神经回路和计算调节气味运动检测，它们与那些 调节视觉运动检测？我们将通过结合光遗传刺激、神经元 活动测量，以及使用我们使用的行为和计算框架的神经遗传学沉默 来发现气味运动感应。利用这个平台，我们可以对真实气味和虚拟气味进行控制、测量和扰动 在自由行走的苍蝇的嗅觉导航过程中，闭环和开环中的气味信号。果蝇是完美的 适合于追求这些目标，因为1)目前对嗅觉外周神经回路的了解 以及下游嗅觉中心的日益增多，以及连接体的可用性；以及(2) 选择性地测量和操纵参与感觉处理和整合的神经回路的活动。 苍蝇使用气味运动检测来增强气味引导导航的发现揭示了我们在 对嗅觉导航的理解。这项拟议的研究将通过描述苍蝇是如何 将气味运动与其他线索结合起来，指导嗅觉行为，并通过揭示神经回路和 调节气味运动检测的计算。更广泛地说，这些发现将促进我们的理解 通过允许我们比较计算不同模式的运动的电路 嗅觉和视觉，它们从具有非常不同的统计数据的输入中获得这些信号，并将它们用于不同的 航海目的。

Many animals rely on their ability to navigate to the source of airborne odor plumes for survival. Studies dating back a century have shown that insects combine mechanosensory and olfactory cues to navigate, surging upwind when detecting odor but go crosswind or downwind when losing the signal. They also use bilateral information from their two antennae to turn toward higher odor concentrations. We recently discovered that in addition to wind direction and odor gradient, fruit flies detect the direction of motion of odors, independent of the wind. Using optogenetics to decouple odor signal from wind, we found that flies detect odor motion using the temporal correlations of the odor signal between their two antennae, suggesting similarities with motion detection in vision. Manipulating spatio-temporal correlations in virtual odor signals demonstrated that flies indeed exploit odor motion when navigating odor plumes. The finding that Drosophila melanogaster can ‘smell’ odor motion suggests a novel role for bilateral sensing in olfaction and raises the following questions for the field: 1) How is odor motion — a previously unappreciated olfactory directional cue — integrated with other directional cues to drive olfactory navigation? 2) What are the inputs to the odor motion detector and how does odor valence modulate behavioral response to odor motion? 3) What neural circuits and computations mediate odor motion detection and how do they compare to those that mediate visual motion detection? We will address these questions by combining optogenetic stimulation, neuron activity measurements, and neurogenetic silencing with the behavioral and computational framework we used to discover odor motion sensing. With this platform we can control, measure, and perturb real odor and virtual odor signals in closed- and open-loop, during olfactory navigation of freely walking flies. Drosophila is perfectly suited to pursue these goals because of 1) the current knowledge of the neural circuit of the olfactory periphery and increasingly of downstream olfactory centers, and the availability of a connectome; and (2) the ability to selectively measure and manipulate the activity of neural circuits involved in sensory processing and integration. The finding that flies use odor motion detection to enhance odor-guided navigation reveals important gaps in our understanding of olfactory navigation. The proposed research will close these gaps by characterizing how flies integrate odor motion with other cues to direct olfactory behavior, and by uncovering the neural circuits and computations that mediate odor motion detection. More broadly, these findings will advance our understanding of neuronal circuit computations by allowing us to compare circuits that compute motion across the modalities of olfaction and vision, which derive these signals from inputs with very different statistics and use them for different navigational purposes.