Organization of Excitatory and Inhibitory Circuits in ASD

描述（由申请人提供）：来自不同实验的汇聚证据表明，兴奋和抑制的平衡在自闭症中被破坏，对神经通信产生广泛影响。该项目的目标是研究在前额叶网络中兴奋性和抑制性控制的神经元的完整性这一基本上未被探索的问题。实验将在来自3- 10岁儿童的死后脑组织上进行，使用强健互连的前扣带、眶额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，而这些在自闭症中一直受到影响。总体假设是，自闭症患者大脑连接性的改变以不同的方式影响短期和长期的额叶皮质通路和局部抑制性神经元，扰乱神经通讯以及兴奋和抑制的平衡。这一假设将通过调查以下情况来检验：（1a）深层白色物质中的兴奋性轴突，其将前额叶皮层与远处区域联系起来，在自闭症中是去神经化的;（1b）浅层白色物质中的兴奋性轴突及其生长相关蛋白GAP-43的表达，其将邻近的前额叶区域联系起来，在自闭症儿童中是扩大的;（2）兴奋性轴突及其GAP-43在不同皮质层中的表达，所述皮质层接收或发出自闭症前额叶皮质中的驱动前馈或调节反馈通路，以及（3）前额叶灰质中的三种功能不同的神经化学类抑制性神经元的层状组成和关系，这是皮质抑制性控制的基础。数据将用于：（4）计算模拟额叶回路的复杂相互作用，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会被破坏。选择3-10岁的年龄，目的是捕捉记录的非典型和典型的前额叶皮层的自闭症儿童和控制。轴突将被髓鞘和GAP-43双重标记，GAP-43在发育和脑损伤后表达，用于在光学、共聚焦和电子显微镜下研究，并将在3D中重建。将标记抑制性神经元，以通过其神经化学和已知的神经支配模式区分功能类别。研究结果将提供一个丰富的定量数据库的兴奋性轴突和抑制性神经元的自闭症儿童的大脑中的功能与年龄匹配的控制和持续变化的轴突在前额叶白色问题的自闭症成人的可用数据进行比较。跨年龄的比较将有助于描绘自闭症发展变化的时间轴，并有助于设计未来的实验来研究早期轴突生长或持续炎症是否可能是病理学的基础。拟议的研究将提供新的数据，神经元的精细功能，以模拟自闭症的兴奋抑制和神经通信中断。这些发现将对自闭症治疗干预的发展产生重要影响。

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.