EngramSeq: a new technology for mapping engram networks in mice

EngramSeq：一种绘制小鼠印迹网络的新技术

• 批准号: RGPIN-2022-03509
• 负责人: Josselyn, Sheena
• 金额: $ 5.68万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764255
• 关键词: EngramSeq; new; technology; mapping; engram

My lab studies how the brain encodes, stores and uses information. One arm of my research program examines how memory goes wrong in disease states (e.g., Alzheimer's disease or PTSD) and is funded by CIHR. The second arm focuses on fundamental basic processes underlying information processing. This arm has been continuously supported by NSERC since I began my lab in 2005. My recently completed NSERC Discovery grant supported the development and test-driving of an open-source mini-endoscope that allows neuronal activity to be visualized in the brain of freely-behaving mice as they learn and remember. With this technology, we can literally "watch the brain of a mouse as it remembers". I am gratified that many of the diverse trainees involved in this project have gone on to further careers in science (Google Deep Mind, two biotech start-ups, and an Assistant Professor). In the current proposal, we will also develop a new open-source tool. EngramSeq will allow us to visualize where specific memory "engram" cells project in the brain. The brain is likely one of the most complex objects in the universe. The human brain contains roughly 100 billion neurons linked together by some 100 trillion synaptic connections while the mouse brain contains roughly 70 million neurons. Fundamental brain functions including memory likely derive from the patterns of connections between neurons. However, our knowledge of the overall brain wiring diagram is limited. To better understand the brain in all of its complexity, it is important to unravel the vast tangle of different neuronal projections. Recently, a technique was developed that exploits high-throughput DNA sequencing to allow the projection profile of thousands of individual neurons to be analyzed in the same mouse brain (Kebschull et al., 2016). This technique, called MAPseq (multiplexed analysis of projections by sequencing), uses unique RNA "barcodes" to identify the projection patterns of thousands of neurons at a time. Although MAPseq is a powerful tool, it has two limitations that preclude its use in our (and likely many) studies. First, the viral vector used to express the barcode is toxic and kills infected neurons within 3 days. Second, it is not possible to "target" barcode expression to specific neurons of interest. To address these limitations, we will develop EngramSeq to examine the specific projections of different individual engram neurons. This multidisciplinary project is ideal for training highly-qualified personnel as trainees will gain expertise in molecular biology, sequencing, mouse brain surgery, mouse behaviour, and big data analysis. Importantly EngramSeq will be a versatile tool that can be applied not only to our research questions (where do different engram neurons project?), but also be applied to other questions posed by the broader neuroscientific community. Our goal is that our new open-science tool will also be valuable to the neuroscience research community at large.

我的实验室研究大脑如何编码、存储和使用信息。我的研究项目之一是研究疾病状态（例如阿尔茨海默病或创伤后应激障碍）下记忆如何出错，并由 CIHR 资助。第二部分侧重于信息处理的基本过程。自 2005 年我开始我的实验室以来，这条手臂一直得到 NSERC 的持续支持。我最近完成的 NSERC Discovery 资助支持了开源迷你内窥镜的开发和测试，该内窥镜允许在自由行为的小鼠学习和记忆时，将其大脑中的神经元活动可视化。有了这项技术，我们就可以“观察老鼠的大脑如何记忆”。我很高兴参与该项目的许多不同的学员都继续从事科学领域的职业生涯（Google Deep Mind、两家生物技术初创公司和一名助理教授）。在当前的提案中，我们还将开发一个新的开源工具。 EngramSeq 将使我们能够可视化特定记忆“印迹”细胞在大脑中的投射位置。大脑可能是宇宙中最复杂的物体之一。人脑包含约 1000 亿个神经元，通过约 100 万亿个突触连接连接在一起，而小鼠大脑包含约 7000 万个神经元。包括记忆在内的基本大脑功能可能源自神经元之间的连接模式。然而，我们对整个大脑接线图的了解是有限的。为了更好地理解大脑的复杂性，解开不同神经元投射的巨大混乱非常重要。 最近，开发了一种利用高通量 DNA 测序的技术，可以在同一小鼠大脑中分析数千个单个神经元的投影轮廓（Kebschull 等人，2016）。这项技术称为 MAPseq（通过测序对投影进行多重分析），使用独特的 RNA“条形码”一次识别数千个神经元的投影模式。 尽管 MAPseq 是一个强大的工具，但它有两个局限性，妨碍了它在我们（以及可能的许多）研究中的使用。首先，用于表达条形码的病毒载体是有毒的，会在 3 天内杀死受感染的神经元。其次，不可能将条形码表达“定位”到感兴趣的特定神经元。为了解决这些限制，我们将开发 EngramSeq 来检查不同个体印迹神经元的特定投影。这个多学科项目非常适合培训高素质人才，因为学员将获得分子生物学、测序、小鼠脑手术、小鼠行为和大数据分析方面的专业知识。重要的是，EngramSeq 将是一种多功能工具，不仅可以应用于我们的研究问题（不同的印迹神经元投射到哪里？），还可以应用于更广泛的神经科学界提出的其他问题。我们的目标是，我们新的开放科学工具也将对整个神经科学研究界有价值。