Organization of Excitatory and Inhibitory Circuits in ASD

描述(申请人提供)：来自不同实验的汇聚证据表明，自闭症患者的兴奋和抑制的平衡被破坏，并对神经交流产生广泛的影响。拟议项目的目标是研究在前额叶网络中兴奋和抑制控制的神经元件的完整性，这一问题在很大程度上是未知的。实验将在3-10岁儿童的身体脑组织上进行，使用紧密相连的前扣带回、眶前叶和外侧前额叶皮质作为模型系统。这些区域在注意力、情绪和行为灵活性的过程中起着关键作用，而自闭症患者的注意力、情绪和行为灵活性一直受到影响。最重要的假设是，自闭症患者大脑连通性的改变以不同的方式影响短期和远程额叶皮质通路和局部抑制性神经元，扰乱神经交流以及兴奋和抑制的平衡。这一假说将通过调查以下情况来检验：(1a)在自闭症患者中连接前额叶皮质与远处区域的深层白质中的兴奋性轴突；(1b)在自闭症儿童中连接邻近前额叶区域并被放大的浅层白质中的兴奋性轴突及其生长相关蛋白GAP-43的表达；(2)自闭症患者前额叶皮质中接受或发出驱动前馈调节反馈通路的不同皮质层中的兴奋性轴突及其表达，以及；(3)前额叶灰质内三类不同功能的抑制性神经元的板层组成和相互关系，它们是皮层抑制控制的基础。数据将被用于：(4)对额叶电路的复杂相互作用进行计算建模，这些相互作用与注意力和情绪过程的整合有关，以及灵活转移注意力的能力，这在自闭症谱系中通常是被干扰的。选择3-10岁的年龄旨在捕捉自闭症儿童和对照组儿童前额叶皮质有记录的非典型和典型发育。轴突将被双重标记髓鞘和在发育过程中和脑损伤后表达的GAP-43，用于在光学显微镜、共聚焦显微镜和电子显微镜下进行研究，并将在3D中重建。抑制神经元将被标记，以根据它们的神经化学和已知的神经支配模式来区分功能类别。这些发现将为自闭症儿童大脑中兴奋性轴突和抑制性神经元的特征提供丰富的量化数据库，以与年龄匹配的对照组进行比较，并提供有关自闭症成人前额叶白质轴突持续变化的现有数据。跨年龄的比较将有助于描绘自闭症发育变化的时间表，并有助于设计未来的实验，以研究早期轴突生长或持续性炎症是否可能是病理的基础。所提出的研究将为模拟自闭症患者的兴奋-抑制和神经通讯中断提供关于神经元件精细特征的新数据。这一发现将对自闭症治疗干预的发展具有重要意义。

DESCRIPTION (provided by applicant): Converging evidence from diverse experiments suggests that the balance of excitation and inhibition is disrupted in autism with widespread repercussions on neural communication. The goal of the proposed project is to investigate the largely unexplored issue of the integrity of neural elements that underlie excitatory and inhibitor control within prefrontal networks. Experiments will be conducted on post-mortem brain tissue from 3- 10 year old children, using the robustly interconnected anterior cingulate, orbitofrontal, and lateral prefrontal cortices as a model system. These areas have a key role in the processes of attention, emotions and behavioral flexibility, which are consistently affected in autism. The overarching hypothesis is that altered brain connectivity in autism affects in distinct ways short and long-range frontal cortical pathways and local inhibitory neurons, disrupting neural communication and the balance of excitation and inhibition. This hypothesis will be tested by investigating the status of: (1a) excitatory axons in the deep white matter that link prefrontal cortices with distant areas, which are desynchronized in autism; (1b) excitatory axons and their expression of the growth-associated protein GAP-43 in the superficial white matter, which links neighboring prefrontal areas and is enlarged in children with autism; (2) excitatory axons and their expression of GAP-43 in different cortical layers that receive or issue driving feedforward o modulatory feedback pathways in prefrontal cortices in autism, and; (3) the laminar composition and relationships of three functionally distinct neurochemical classes of inhibitory neurons in prefrontal grey matter, which underlie cortical inhibitory control. Data will be used to: (4) computationally model complex interactions of frontal circuits, associated with the integration of attentional and emotional processes, and the ability to flexibly shift attention, which are commonly disrupted across the autism spectrum. The choice of ages 3-10 years aims to capture documented atypical and typical development of the prefrontal cortex of children with autism and controls. Axons will be double-labeled for myelin, and for GAP-43, which is expressed in development and after brain injury, for study at the light, confocal, and electron microscopes, and will be reconstructed in 3D. Inhibitory neurons will be labeled to distinguish functional classes by their neurochemistry and known mode of innervation. Findings will provide a rich quantitative database on the features of excitatory axons and inhibitory neurons in the brains of children with autism to compare with age-matched controls and with available data of persistent changes in axons in the prefrontal white matter of adults with autism. Comparison across ages will help delineate a timeline for the developmental changes in autism, and help design future experiments to study whether early axon growth or persistent inflammation may underlie the pathology. The proposed studies will provide novel data on fine features of neural elements to model the disrupted excitation-inhibition and neural communication in autism. The findings will have important implications for the development of therapeutic interventions in autism.