Probing brain network dynamics in freely behaving animals

在过去的十年里，神经科学见证了利用基于光的工具来可视化和操纵大脑活动的新技术的爆炸性增长。结合强大的基因方法，允许有针对性地表达基于光的蛋白质致动器或发光活动记者，该领域现在有能力达到以前无法想象的水平，并洞察自由行为的动物的工作大脑。我们和卡尔加里大学的其他人利用这些方法获得了关于社会行为、对威胁的防御性反应或脑血流控制的新知识。这些洞察力需要数据分析管道、计算工具和机器学习方法的并行开发。这是全球性的努力，但卡尔加里的研究人员正在取得重大进展。 目前，我们有能力：1)使用基因表达的钙指示剂，如GCaMP，记录大脑中细胞群的活动，允许观察遗传识别的细胞群中的钙波动；或：2)使用光遗传学方法操纵活动，(特定细胞群的离散激活或抑制)。神经活动是使用微型显微镜记录的，这种显微镜允许在一次销售的分辨率下实时读出行为自由的动物的活动读数。活动是通过植入的光纤来控制的，这些光纤允许在特定波长传输光来激活或抑制细胞。这些平行的信息流提供了重要的信息，但我们不能在同一实验中观察和操纵细胞活动，这意味着将两种方法联系起来是推论的。 在这里，我们请求为两个nVoke微型显微镜系统提供资金，这两个系统将同时进行活动采样和在单个头盔单元中进行操作。这些将升级现有的仅具有成像功能的Inscope ix微型显微镜。例如，我们将使用该设备来记录和干扰社交和防御行为中的PVNCRH活动，并允许我们确定特定PVNCRH神经元到一个大脑目标的离散投射是否中介了一种行为(社交方法)与另一种行为(防御性逃避)。这将提供新的信息，开始推进和测试与PVNCRH群体功能异质性相关的想法，并导致对防御、社会和应激行为的更有针对性的操纵。升级后的设备将安置在CSM光遗传学核心设施中，在那里将由训练有素的科学家人员监督。这也将允许其他研究小组访问该设备，进行其他将大脑回路和行为联系起来的探索。

Over the past decade, neuroscience has seen an explosion of new techniques that leverage light-based tools to visualize and manipulate brain activity. Combined with powerful genetic methods that allow for targeted expression of light-based protein actuators or light-emitting activity reporters, the field now has the ability for a formerly unthinkable level of precision and insight into the working brain in freely behaving animals. We, and others at the University of Calgary have leveraged these approaches to gain new knowledge about social behavior, defensive responses to threat or control of brain blood flow. These insights have required the parallel development of data analysis pipelines, computational tools and machine learning approaches. This is global effort, but significant inroads are being made by researchers in Calgary. Currently, we have the capacity to either: 1) record activity of cell populations in the brain using genetically expressed calcium indicators, such as GCaMP, that allow for the observation of calcium fluctuations in genetically identified cell populations, or: 2) manipulate activity, (discrete activation or inhibition of defined cell populations) using optogenetic approaches. Neural activity is recorded using miniature microscopes that allow for real-time activity readouts in a freely behaving animal at the resolution of a single sell. Activity is manipulated using implanted optical fibres that allow for the delivery of light at specific wavelengths to activate or inhibit cells. These parallel information streams offer important information but we cannot observe and manipulate cell activity in the same experiment, which means that linking the two approaches is inferential. Here we request funding for two nVoke miniature microscopy systems that combine simultaneous activity sampling with manipulation in a single head-mounted unit. These will upgrade existing Inscopix miniature microscopes that have imaging only capabilities. As one example, we will use this equipment to record and perturb PVNCRH activity during social and defensive behaviors and allow us to determine whether discrete projections from specific PVNCRH neurons to one brain target mediate one behavior (social approach) vs another (defensive escape). This will provide new information that begins to advance and test ideas related to functional heterogeneity in PVNCRH populations and lead to more targeted manipulations of defensive, social and stress behaviors. The upgraded equipment will be housed in the CSM Optogenetics Core Facility where it will be under the oversight of trained staff scientists. This will also allow other research groups to access this equipment for other explorations linking brain circuits and behavior.