Analysis of integrated brain functions using hemogenetic imaging

功能磁共振成像(FMRI)等血液动力学神经成像方法具有革命性-- 通过允许研究人员描述人的全脑活动的时空特征，神经科学 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的解释性见解的能力。致信地址 为了解决这个问题，我们最近开发了一种史无前例的可遗传编码的分子探针家族，称为 致病因子，将细胞内钙活动转化为人工血流动力学反应，允许在空间上 基因靶向细胞和电路元件的全面神经成像。血液生成信号的产生 可通过药理学手段与内源性血流变化相鉴别 可通过任何血流动力学成像设备检测到。我们的初步实验表明，细胞特异性 甚至稀疏的神经元群体的活动可以用血源性fMRI来识别。这些能力将 使血液成像能够面对神经科学中一些最突出的问题，例如去核磁共振 在全脑范围内刻画离散细胞群体的功能属性，定义输入-输出关系- 在相互作用的大脑区域和神经回路组件之间运输，并将行为和活动与Plas- 在整个大脑中发生的可塑性和基因表达的变化。在这个项目中，我们将使用血源性 在啮齿动物感觉功能的背景下，进行成像以解决这些广泛的问题，同时同时 时间提炼技术，为其在众多研究课题和模型中的更广泛应用奠定基础 神经科学中的系统。 在目标1中，我们提出将该技术用于研究体检中的网络级处理-- 这是一套完整的系统。预期结果将为首个多区域刺激处理模型提供信息，该模型符合... 取代传统相关功能连接措施的数据驱动替代方案。我们将使用此模型 研究反馈关系的重要性并帮助解释感觉适应现象 以及在网络级别上的显著编码。在目标2中，我们将通过应用NOSTIC探测器来利用这一能力 前爪刺激和休息时兴奋性和抑制性神经亚型的基因靶向功能磁共振成像 大鼠的状态动力学，解决关于不同类型细胞的功能作用的假说。此外, 我们将应用超高分辨率fmri来检查单支血管水平血流动力学之间的关系。 以及NOSTIC表达的细胞类型特定分布，使丰富的分析同时在- 对常规fMRI结果的形式解释，并严格表征血液病的表现 技术本身。在目标3中，我们建议改进NOSTIC记者本身。我们计划的改进将 提高血液信号的可探测性，产生有用的血液基因报告 用于绘制未来应用中的神经连通性和可塑性。

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.