Ultrastructural visualisation of synaptic function in brains of behaving mice

行为小鼠大脑突触功能的超微结构可视化

• 批准号: BB/W008882/1
• 负责人: Michael Hausser
• 金额: $ 97.5万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW008882%2F1
• 关键词: Ultrastructural; visualisation; synaptic; function; brains

The basic function of the brain is to process information to trigger action: receiving sensory input and integrating it with prior experience to generate appropriate responses. The information is encoded in the form of small electrical activity signals that are passed between specialized cells (neurons) wired up together to form circuits. To understand how neurons are able to compute their responses - the essence of a working brain - we need to know two key things: (1) how neurons are connected together (the 'wiring pattern'), and (2) what signals are occurring at the specialized neuronal connection points, called synapses, as an animal carries out behaviours. It is essential to understand both elements: identify "who is talking to who", and also identify which synapses are active and how strong they are - in order to understand how the brain works. When examining the large and richly interconnected networks in mammalian brains, solving these problems is a major challenge. This has severely limited our understanding of brain operation. Recently, researchers have found a way to address the problem of identifying synaptic connections between neurons using a special type of electron microscope which allows a target brain region to be reconstructed in three-dimensional detail down to nanometre resolution, an approach called 3D-EM. When combined with powerful computational analysis approaches, it then becomes possible to map out the neuronal connections in a circuit and therefore reveal the wiring diagram. What is still missing, however is the functional information at the synapses - their strength and pattern of activation - that is essential for a full understanding of circuit operation.The aim of this project is to address problems (1) and (2) in parallel by developing state-of-the-art approaches to provide us with a revolutionary new way to read out synaptic activity and strength using 3D-EM. We will apply our methods in the planned work to generate, for the first time, functional maps of synaptic activity overlaid onto the wiring diagram of the same circuit as an animal processes sensory (visual) inputs and performs complex behaviours. In our pilot experiments we have already shown that our technique can be used to reliably identify synapses and estimate their strength. We will optimise this strategy and combine it with powerful new machine-learning technologies for computer-based image analysis which will be developed as part of the research program. This will permit an automated analysis of tens of thousands of structures in a 3D brain tissue volume that is both much faster and yields better accuracy and reproducibility than is achievable by expert humans.These ground-breaking new methodologies should give us fundamental insights into the relationship between the function of individual synapses and behaviour - a holy grail in the field of systems neuroscience. In the future, our unique methodology may also be used to examine the disorders in information signalling that occur in neurodegenerative diseases, offering potential targets for therapeutics. The findings and the topic are very well-aligned with current BBSRC initiatives including the Research and Innovation Priority, 'Advancing the frontiers of bioscience discovery', which includes 'Understanding the rules of life' and 'Transformative technologies' as two of its principal aims. Our core objectives are also directly relevant to the BBSRC responsive mode priorities 'Data-driven biology', 'Technology development for the biosciences' and 'Systems approaches to the biosciences'.

大脑的基本功能是处理信息以触发行动：接收感官输入并将其与先前的经验相结合以产生适当的反应。这些信息被编码成小的电活动信号，在连接在一起形成电路的特殊细胞（神经元）之间传递。为了理解神经元是如何计算它们的反应的——这是大脑工作的本质——我们需要知道两个关键的事情：(1)神经元是如何连接在一起的（“布线模式”），(2)当动物执行行为时，在称为突触的特殊神经元连接点上发生了什么信号。理解这两个要素至关重要：确定“谁在和谁说话”，同时确定哪些突触是活跃的，它们有多强——这样才能理解大脑是如何工作的。在研究哺乳动物大脑中庞大而丰富的互联网络时，解决这些问题是一项重大挑战。这严重限制了我们对大脑运作的理解。最近，研究人员已经找到了一种方法来解决识别神经元之间突触连接的问题，使用一种特殊类型的电子显微镜，这种显微镜允许目标大脑区域以三维细节重建到纳米分辨率，这种方法被称为3D-EM。当与强大的计算分析方法相结合时，就有可能绘制出电路中的神经元连接，从而揭示接线图。然而，仍然缺少的是突触的功能信息——它们的强度和激活模式——这对于充分理解回路的运作至关重要。该项目的目的是通过开发最先进的方法来解决问题(1)和(2)，为我们提供一种革命性的新方法来读取使用3D-EM的突触活动和强度。我们将在计划的工作中首次应用我们的方法，生成覆盖在与动物处理感觉（视觉）输入和执行复杂行为相同的电路接线图上的突触活动功能图。在我们的初步实验中，我们已经证明了我们的技术可以用来可靠地识别突触并估计它们的强度。我们将优化这一策略，并将其与基于计算机的图像分析的强大的新机器学习技术相结合，这将作为研究计划的一部分进行开发。这将允许在3D脑组织体积中对数万个结构进行自动分析，这比专家可以实现的更快，准确度和可重复性更好。这些突破性的新方法应该让我们对单个突触的功能和行为之间的关系有了基本的了解——这是系统神经科学领域的圣杯。在未来，我们独特的方法也可用于检查神经退行性疾病中发生的信息信号紊乱，为治疗提供潜在的靶点。这些发现和主题与目前BBSRC的计划非常吻合，包括研究和创新优先事项，“推进生物科学发现的前沿”，其中包括“理解生命规则”和“变革技术”作为其两个主要目标。我们的核心目标也与BBSRC响应模式优先事项“数据驱动的生物学”、“生物科学的技术开发”和“生物科学的系统方法”直接相关。