Individual Variation in Effects of Traumatic Stress on Gray Matter Myelin

项目摘要/摘要 这项研究将考察适应不良髓鞘形成作为支持结构和功能的潜在机制。 与创伤应激暴露相关的功能性脑异常。具体来说，我们将探索 对创伤应激引起的急性威胁(“恐惧”：RDoC领域)持续敏感背后的机制 在成年初期。髓鞘形成很可能是为了提高传导速度，但在灰质(GM)， 它减少轴突萌发、突触密度和神经可塑性。令人振奋的最新发现表明 皮质和皮质下灰质中的髓鞘发育是高度可塑性的，并受到新的 经历和学习，即使在成年生活中也是如此。重要的是，形成髓鞘的少突胶质细胞对 环境应激源，因此可能提供一种新的机制，通过这种机制异常的结构和 大脑会发生功能变化。 我们实验室的人脑成像数据显示，患有一系列继发性创伤后应激障碍症状的受试者 成人创伤暴露增加了海马体(HP)、额叶和颞叶GM中的髓鞘含量。 重要的是，髓磷脂含量预测症状严重程度超过了潜在的混杂变量。 此外，我们发现，在啮齿动物中暴露于成年创伤应激会增加 少突胶质细胞(OG)和齿状回(DG)中的髓鞘含量是GM结构。与人类相似 受试者，我们的初步数据显示，大鼠的症状严重程度(恐惧分数)与DG显著相关 OGS和髓鞘含量。总体而言，这些发现提供了一个转换模型，以更好地理解 人类少突胶质细胞和髓鞘可塑性的机制。在这个提案中，我们将检验这一假设 成年期间的创伤应激暴露会导致皮质和皮质下GM髓鞘形成增加 在恐惧记忆的关键区域。具体地说，我们预计只有在那些 随后对压力暴露后的严重威胁变得敏感。此外，我们假设 髓鞘形成增加将限制主要内在功能连接(IFC)的正常功能。 网络。这种动物-人类的综合设计使创新的多层次和因果探索成为可能。 此外，我们着重于成人大脑中髓鞘可塑性作为创伤诱导的中介的新作用。 严重威胁症状。 目的1集中在海马灰质髓鞘形成是否能预测创伤后的问题。 对严重威胁的敏感性。目标2的重点是创伤暴露是否对 皮质和皮质下GM髓鞘形成预测网络连通性和恐惧记忆。

PROJECT SUMMARY/ABSTRACT This research will examine maladaptive myelination as a potential mechanism underpinning the structural and functional brain abnormalities associated with exposure to traumatic stress. Specifically, we will explore the mechanisms behind persistent sensitivity to acute threat (“fear”: RDoC domain) arising from traumatic stress during early adulthood. Myelination most likely evolved to improve conduction velocity but in gray matter (GM), it reduces axonal sprouting, synaptic density, and neuroplasticity. Exciting recent findings have shown that myelin development in both cortical and subcortical gray matter is highly plastic and strongly influenced by new experiences and learning, even during adult life. Importantly, myelin-forming oligodendrocytes are sensitive to environmental stressors and therefore may provide a novel mechanism by which aberrant structural and functional changes arise in the brain. Human brain imaging data from our labs show that subjects with a range of PTSD symptoms secondary to adult trauma exposure have increased myelin content in the hippocampal (HP), frontal, and temporal GM. Importantly, myelin content predicted symptom severity over and above potential confounding variables. Furthermore, we found that adult traumatic stress exposure in rodents produces an increase in oligodendrocytes (OGs) and myelin content in the dentate gyrus (DG), a GM structure. Similar to human subjects, our preliminary data show that symptom severity (fear score) in rats is significantly correlated with DG OGs and myelin content. Overall, these findings provide a translational model to better understand the mechanisms of oligodendrocyte and myelin plasticity in the human. In this proposal, we will test the hypothesis that traumatic stress exposure during adulthood leads to increased myelination in cortical and subcortical GM in regions critical for fear memory. Specifically, we expect to see this increased myelination only in those that subsequently become sensitive to acute threat following stress exposure. Additionally, we hypothesize that increased myelination will constrain the proper functioning of the major intrinsic functional connectivity (IFC) networks. This integrated animal-human design enables an innovative multilevel and causal exploration. Additionally, we focus on a novel role for myelin plasticity in the adult brain as a mediator of trauma-induced acute threat symptoms. Aim 1 is focused on the question of whether hippocampal gray matter myelination predict post-trauma sensitivity to acute threat. Aim 2 is focused on the question of whether the effects of trauma exposure on cortical and subcortical GM myelination predict network connectivity and fear memory.