Optical tools to probe neural circuits in the echolocating bat

项目摘要/摘要： 神经科学的一个主要目标是剖析支持复杂行为的神经回路。比较 方法是成功实现这一目标的基础，将物种专门化与一般原则分开，以及 根据大脑进化的功能来理解大脑。使电路神经科学发生革命性变化的光学工具 必须扩大啮齿动物的研究范围，以研究更广泛的物种。在这里，我们建议开发技术来绘制地图 回声定位蝙蝠自下而上和自上而下的感觉回路，这种动物一直是 进一步加深了我们对大脑在自然条件下是如何运作的理解。蝙蝠使用主动感知来达到它的目标 定向狩猎行为，使其声纳信号设计适用于在3D环境中搜索、跟踪和拦截目标。 在这里，我们将优化分子和光学工具，以确定自下而上和自上而下电路如何控制两者 长时间尺度行为模式转换和短时间尺度行为适应。通过这些努力，我们还将 使利用分子工具对回声定位蝙蝠进行电路解剖的广泛新实验成为可能。 最初，我们的重点将放在中脑上丘(SC)。SC对人类的刺激选择至关重要 以及将关于物体相对位置的感觉信息转换为运动 用于定向的命令。在蝙蝠中，SC适应于声音定向，因此对动物的 自然的目标搜索、跟踪和拦截行为。SC是一个综合中枢，接受自下而上的感觉 下丘(IC)和自上而下的听觉皮质(AC)投射。在过去的研究中，我们发现 蝙蝠SC中的神经元选择自然声音而不是人工刺激。然后，我们率先从SC录制了 当蝙蝠的行为被适应来跟踪和选择目标时，它们会发现动态的感觉和运动编码。在……里面 我们提出的工作，我们将测试的假设是，IC-AC-SC电路是关键的之间的切换行为 模式(例如搜索、跟踪和拦截)，以及基于感觉反馈的精细运动调整 在行为模式下。这种类型的电路解剖需要使用光学工具，而目前在 蝙蝠和它的发展是这辆R34的重点。具体地说，我们提出了钙成像的发展 测试广泛电路激活的技术，以及针对电路级活动的细胞特定操纵的光遗传学。 为了进行这些研究，我们首先确定了不同病毒工具靶向细胞类型的可行性。 和球棒中的巡回赛。我们现在正在使用我们优化的AAV系统来验证双光子钙的适用性 用于监测蝙蝠神经网络的成像，更长期的目标是展示光遗传学如何用于 对不同电路元件在行为模式切换和自适应中的作用进行因果推断 行为控制。最后，我们将开发工具来实现无线、无电池的光遗传刺激 改变蝙蝠在真实3D环境中的自然行为的电路特性的设备。通过这些 经过努力，我们将处于有利地位，随后将有针对性地追求大脑电路项目R01来解剖神经电路 通过对啮齿动物和蝙蝠的比较研究，支持适应性感觉运动行为。

PROJECT SUMMARY/ABSTRACT: A major goal in neuroscience is to dissect the neural circuits that support complex behaviors. Comparative approaches are fundamental to the success of this goal, to separate species specializations from general principles, and to understand the brain in light of its evolved functions. The optical tools that have revolutionized circuit neuroscience in rodents must be expanded to investigate a broad range of species. Here, we propose to develop technologies to map out bottom‐up and top‐down sensory circuits in the echolocating bat, an animal that has been an important tool for furthering our understanding how the brain operates under natural conditions. The bat uses active sensing for its goal directed hunting behaviors to adapt its sonar signal design to search, track and intercept targets in the 3D environment. Here, we will optimize molecular and optical tools to determine how bottom‐up and top‐down circuits control both long‐time scale behavioral mode switching and short time‐scale behavioral adaptation. With these efforts we will also enable a wide‐range of new experiments that exploit molecular tools for circuit dissection in the echolocating bat. Initially, our focus will be on the midbrain superior colliculus (SC). The SC is critical for stimulus selection in humans and other animals, as well as for converting sensory information about the relative location of an object into motor commands for orienting. In the bat, the SC is adapted for acoustic orienting, and is therefore important to the animal's natural target search, tracking, and interception behaviors. The SC is an integrative hub receiving bottom‐up sensory input from the inferior colliculus (IC) and top‐down projections from the auditory cortex (AC). In past studies, we found that neurons in the bat SC select for natural sounds over artificial stimuli. We then pioneered recordings from the SC of behaving bats and found dynamic sensory and motor coding when behavior was adapted to track and select targets. In our proposed work, we will test the hypothesis that the IC‐AC‐SC circuit is critical for both switching between behavioral modes (e.g. search, tracking, and interception), as well as fine‐scale motor adjustments based upon sensory feedback within a behavioral mode. This type of circuit dissection requires the use of optical tools that are currently unavailable in the bat and whose development is the focus of this R34. Specifically, we propose the development of calcium imaging techniques to assay broad circuit activation, and optogenetics for cell‐specific manipulations of circuit‐level activity. To pursue these lines of investigation, we first established the feasibility of different viral tools to target cell types and circuits in the bat. We are now using our optimized AAV system to validate the applicability of two‐photon calcium imaging for monitoring neural networks in bats, with a longer‐term goal of showing how optogenetics can be used to make causal inferences about the role of different circuit components in behavioral mode switching and adaptive behavioral control. Finally, we will develop the tools to enable the use of wireless, battery free optogenetic stimulation devices to alter circuit properties in bats engaged in natural behaviors in the real, 3D environment. Through these efforts, we will be well positioned to subsequently pursue a Targeted Brain Circuits Projects R01 to dissect neural circuits supporting adaptive sensorimotor behaviors through comparative studies of rodents and bats.