Two-photon analysis of circuit-level mechanisms of schizophrenia biomarkers

 描述(由申请人提供)：在过去的几十年里，对精神分裂症(SZ)的生物基础的研究集中于确定该疾病的经验标记，这些标记比诊断所基于的现象学症状更接近病因学过程。这些生物标记物提示感觉皮质处理的根本性中断，有可能解释该疾病的现象学和更高级别的认知方面，并为有针对性的临床干预提供关键的翻译策略。尽管有一些令人鼓舞的线索，但我们仍然不了解大多数生物标志物背后的病理生理学，也不知道这些测量本身如何与大脑皮层回路的基本计算相关，限制了它们作为翻译工具和理论基准的用途。转基因和小鼠光学成像的最新进展提供了令人兴奋的新工具，可以用来回答这些特定的问题。拟议的项目将使用尖端的双光子光学成像和光刺激方法来识别SZ的两个已建立的振荡生物标志物的微电路水平底物：视觉皮质中的阿尔法和伽马波段同步。具体地说，我们将使用小鼠的慢性氯胺酮暴露来建立一个无序的感觉皮质处理模型，并用密集的微电极记录来测量V1的自发和视觉诱发的振荡动力学。然后，我们将(AIM1)使用最先进的快速3D双光子钙离子成像来测量活体皮质微电路的多细胞活性，描述振荡生物标记物如何与局部细胞组合的图案化活动以及与疾病相关的特定抑制性中间神经元亚群的功能相关。基于这些发现，我们将(AIM2)在相同的成像/刺激环境中使用皮质细胞的光遗传操作来评估SZ的振荡生物标记物、电路动力学和局部抑制性中间神经元群体功能之间的随意联系。这些研究将产生：1)用于解释人类测量方法的关键生物力学信息，帮助它们从生物标记物成熟到临床检测；以及ii)这些测量方法及其标记的精神状态(例如SZ)如何与神经活动的新兴模式及其相关的网络水平动力学相关的潜在的新见解。此外，拟议的工作将直接建立在我在精神障碍的感觉生物标记物方面的研究生工作基础上，通过确定这些措施的皮质底物，并将我的专业知识扩展到视觉领域、动物研究、双光子光学成像和光遗传学的光刺激。这项培训将使我能够继续在SZ的遗传小鼠模型中进行后续研究，并进一步探索微电路动力学中断的行为/感知后果、视觉以外的感觉模式以及基于这些生物检测的干预策略。

 DESCRIPTION (provided by applicant): Research into the biological substrate of schizophrenia (SZ) over the past several decades has focused on identifying empirical markers of the disorder which are more proximal to etiological processes than the phenomenological symptomology on which the diagnosis is based. Such biomarkers suggest fundamental disruptions in sensory cortical processing, carry the potential to explain phenomenological and higher order cognitive aspects of the disorder, and provide a critical translational strategy for targeted clinical intervention. Despite some encouraging leads, we still do not understand the pathophysiology behind most biomarkers, or how the measures themselves relate to the essential computations of the cerebral cortical circuit, limiting their utility as translational tols and theoretical benchmarks. Recent advances in transgenic and optical imaging in mice provide exciting new tools with which these specific questions can be answered. The proposed project will use cutting-edge two-photon optical imaging and photostimulation methods to identify the microcircuit level substrate of two established oscillatory biomarkers of SZ: alpha and gamma-band synchronization in visual cortex. Specifically, we will use chronic ketamine exposure in mice to generate a model of disordered sensoricortical processing and measure spontaneous and visually evoked oscillatory dynamics in V1 with dense microelectrode recordings. We will then (AIM1) employ state-of-the-art fast 3D 2- photon Ca2+ imaging to measure the multicellular activity of cortical microcircuits in vivo, describing how oscillatory biomarkers relate to the patterned activity of local cell assemblies and to the function of specific inhibitory interneuron subpopulations with demonstrated disease relevance. Based on these findings, we will then (AIM2) employ optogenetic manipulation of cortical cells in the same imaging/stimulation context to assess casual links between oscillatory biomarkers of SZ, circuit dynamics, and the function of local inhibitory interneuron populations. These studies will yield i) key biomechanistic information for interpreting measures in humans, helping to mature them from biomarkers to clinical assays, and ii) potentially novel insights into how these measures and the psychotic states they mark (e.g. SZ) relate to the emergent patterns of neural activity and their associated network-level dynamics. Moreover, the proposed work will build directly on my graduate work on sensory biomarkers of psychotic disturbance by identifying the cortical substrate of these measures and expanding my expertise into the visual domain, animal research, two-photon optical imaging and photostimutlation with optogenetics. This training will position me to pursue follow-up studies in genetic mouse models of SZ and which further explore the behavioral/perceptual consequences of disrupted microcircuit dynamics, sensory modalities other than vision, and intervention strategies based on these bioassays.