Analysis of Integrated Brain Functions Using Hemogenetic Imaging

血流动力学神经成像方法，如功能性磁共振成像（fMRI），有革命性的- 通过允许研究人员描述人类大脑活动的时空特征， 人和动物然而，这种方法的一个主要缺点是它们缺乏对明确定义的 细胞和分子来源;这限制了他们对神经功能产生解释性见解的能力。解决 为了解决这个问题，我们最近开发了一个前所未有的遗传编码分子探针家族，称为 NOSTICs，将细胞内钙活性转化为人工血流动力学反应， 基因靶向细胞和电路元件的全面神经成像。造血信号出现 可以通过药理学手段将NOSTIC与内源性血流变化区分开来， 可以通过任何血液动力学成像模式检测到。我们的初步实验表明， 甚至稀疏的神经元群体的活动也可以使用造血功能磁共振成像来识别。这些能力将 使造血成像能够面对神经科学中一些最突出的问题，如去- 在全脑范围内描绘离散细胞群的功能特性，定义输入-输出关系- 船舶之间相互作用的大脑区域和神经回路组件，并将行为和活动，以plas- 在整个大脑中发生的活性和基因表达的变化。在这个项目中，我们将使用造血 成像，以解决这些广泛的问题，在啮齿动物的感觉功能的背景下，而在同一时间 不断完善该技术，为该技术在多个研究课题和模型中的广泛应用奠定基础 神经系统科学 在目标1中，我们建议使用该技术来研究体细胞中的网络级处理。 系统。预期的结果将告知第一次的多区域刺激处理模型，包括- 取代了传统的相关功能连接措施的数据驱动的替代方案。我们将使用这个模型 研究反馈关系的重要性，并帮助解释感觉适应现象 和网络级的显著性编码。在目标2中，我们将通过应用NOSTIC探针来利用这种能力 用于前爪刺激和静息期间兴奋性和抑制性神经亚型的遗传靶向fMRI 状态动力学在大鼠中，解决关于不同细胞类型的功能作用的假设。此外，本发明还提供了一种方法， 我们将应用高分辨率功能磁共振成像检查单血管水平血流动力学之间的关系， 以及NOSTIC表达的细胞类型特异性分布，从而能够进行丰富的分析， 形成了对常规fMRI结果的解释，并严格描述了造血功能的表现。 技术本身。在目标3中，我们建议改进NOSTIC报告器本身。我们计划的改进将 增强造血信号的可检测性并产生有用的造血基因报告基因 在未来的应用中映射神经连接和可塑性。

Hemodynamic neuroimaging methods like functional magnetic resonance imaging (fMRI) have revolution- ized neuroscience by allowing researchers to characterize spatiotemporal features of brain-wide activity in hu- mans and animals. A major disadvantage of such approaches, however, is their lack of specificity for well-defined cellular and molecular sources; this limits their ability to yield explanatory insights into neural function. To address this problem, we recently developed an unprecedented family of genetically encodable molecular probes, called NOSTICs, that transduce intracellular calcium activity into artificial hemodynamic responses, permitting spatially comprehensive neuroimaging of genetically targeted cells and circuit elements. Hemogenetic signals arising from the NOSTICs may be differentiated from endogenous blood flow changes by pharmacological means and can be detected by any hemodynamic imaging modality. Our preliminary experiments indicate that cell-specific activity of even sparse neuronal populations can be identified using hemogenetic fMRI. These capabilities will enable hemogenetic imaging to confront some of the most outstanding problems in neuroscience, such as de- scribing functional properties of discrete cell populations on a brain-wide scale, defining input-output relation- ships among interacting brain regions and neural circuit components, and relating behavior and activity to plas- ticity and gene expression changes that occur throughout the brain. In this project, we will use hemogenetic imaging to address each of these broad problems in the context of sensory function in rodents, while at the same time refining the technology and laying a foundation for its wider application to many research topics and model systems in neuroscience. In Aim 1, we propose to use the technology for investigation of network-level processing in the somatosen- sory system. Anticipated results will inform a first-of-its-kind model of multiregional stimulus processing that con- stitutes a data-driven alternative to traditional correlative functional connectivity measures. We will use this model to examine the importance of feedback relationships and to help explain the phenomena of sensory adaptation and salience encoding at the network level. In Aim 2, we will exploit this capability by applying NOSTIC probes for genetically targeted fMRI of excitatory and inhibitory neural subtypes during forepaw stimulation and resting state dynamics in rats, addressing hypotheses about the functional roles of the different cell types. In addition, we will apply ultrahigh resolution fMRI to examine the relationships between single vessel-level hemodynamics and the cell type-specific distributions of NOSTIC expression, enabling a rich analysis that simultaneously in- forms interpretation of conventional fMRI results and rigorously characterizes performance of the hemogenetic technique itself. In Aim 3, we propose to improve the NOSTIC reporters themselves. Improvements we plan will enhance the detectability of hemogenetic signals and give rise to hemogenetic gene reporters that will be useful for mapping neural connectivity and plasticity in future applications.