Organization of Excitatory and Inhibitory Circuits in ASD

描述（由申请人提供）：来自不同实验的证据表明，自闭症中兴奋和抑制的平衡被破坏，对神经交流产生了广泛的影响。该项目的目标是研究前额叶网络中兴奋性和抑制剂控制背后的神经元素的完整性这一尚未探索的问题。实验将在3- 10岁儿童的死后脑组织中进行，使用紧密连接的前扣带皮层、眶额皮层和外侧前额皮质作为模型系统。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，而这些过程在自闭症患者中一直受到影响。最重要的假设是，自闭症患者大脑连通性的改变会以不同的方式影响短期和长期额叶皮质通路以及局部抑制性神经元，破坏神经交流以及兴奋和抑制的平衡。这一假设将通过研究以下状态得到验证：（1a）连接前额皮质和远端区域的深部白质兴奋性轴突，在自闭症中是不同步的；（1b）兴奋性轴突及其在浅层白质中生长相关蛋白GAP-43的表达，该蛋白连接邻近的前额叶区域，并在自闭症儿童中扩大；(2)自闭症患者不同皮质层的兴奋性轴突及其在前额叶皮层接收或发出驱动前馈或调节反馈通路中的GAP-43表达；(3)前额叶灰质中三种功能不同的神经化学抑制神经元的层流组成和相互关系，这是皮层抑制控制的基础。数据将用于：(4)计算模拟额叶神经回路的复杂相互作用，这与注意力和情绪过程的整合以及灵活转移注意力的能力有关，这在自闭症谱系中通常被破坏。选择3-10岁的年龄旨在捕捉记录在案的自闭症和对照组儿童前额叶皮层的非典型和典型发育。轴突将被双重标记为髓磷脂和GAP-43，这是在发育和脑损伤后表达的，用于光学、共聚焦和电子显微镜下的研究，并将在3D中重建。抑制性神经元将通过其神经化学和已知的神经支配模式来标记以区分功能类别。研究结果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定量数据库，以便与年龄匹配的对照组进行比较，并与自闭症成人前额叶白质轴突持续变化的现有数据进行比较。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。本研究将为自闭症患者兴奋抑制和神经交流紊乱的神经元素的精细特征提供新的数据。这一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.