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）生物学基础的研究一直集中在确定该疾病的经验标志物，这些标志物比诊断所依据的现象学病理学更接近病因学过程。这些生物标志物表明感觉皮层处理的根本中断，具有解释障碍的现象学和高阶认知方面的潜力，并为靶向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，或者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实用性。转基因和光学成像在小鼠中的最新进展提供了令人兴奋的新工具，可以回答这些具体的问题。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两个已建立的SZ振荡生物标志物的微电路水平基底：视觉皮层中的α和γ波段同步。具体来说，我们将使用慢性氯胺酮暴露在小鼠中，以产生一个模型的感觉皮层处理紊乱和测量自发和视觉诱发的振荡动力学V1与密集的微电极记录。然后，我们将（AIM 1）采用最先进的快速3D双光子Ca 2+成像来测量体内皮层微电路的多细胞活动，描述振荡生物标志物如何与局部细胞组装的模式化活动以及特定抑制性中间神经元亚群的功能相关，并证明与疾病相关。基于这些发现，我们将在相同的成像/刺激背景下采用皮质细胞的光遗传学操作（AIM 2）来评估SZ的振荡生物标志物、电路动力学和局部抑制性中间神经元群体的功能之间的因果关系。这些研究将产生i）用于解释人类测量的关键生物力学信息，帮助将其从生物标志物成熟为临床测定，以及ii）潜在的新见解，这些测量及其标记的精神病状态（例如SZ）如何与神经活动的涌现模式及其相关的网络水平动态相关。此外，拟议的工作将直接建立在我的研究生工作的感觉生物标志物的精神障碍，通过确定这些措施的皮质基板，并扩大我的专业知识到视觉领域，动物研究，双光子光学成像和光刺激与光遗传学。这项培训将使我能够在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，视觉以外的感觉方式，以及基于这些生物测定的干预策略。

 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.