Anatomical connections subserving the default mode network

描述（由申请人提供）：默认模式网络（DMN）是一组大脑区域，在休息时持续激活，在执行任务时不激活。DMN活动在许多神经和精神疾病中都是异常的，包括重度抑郁症（MDD）和药物成瘾。DMN的两个主要部分是内侧前额叶皮层（mPFC）和后内侧皮层（PMC），这两个区域在空间上相距遥远，具有不同的典型功能。虽然有一些证据表明这些一般皮层区域之间存在直接联系，但人们对它们的具体情况以及它们如何将整个网络连接在一起知之甚少。我假设DMN是通过特定的枢纽子区域连接在一起的，这些子区域包含来自多个DMN区域的聚合连接，而扣带束和内囊是该网络的主要连接白质束。因此，本提案的目标是描述mPFC和PMC之间的解剖连接和通路如何使它们作为一个网络运行。结合传统解剖技术与扩散磁共振成像（dMRI），我将确定DMN的连接。确定这些特定的DMN连接将建立支持神经成像结果的电路。这些基本知识是基础的，是了解疾病中DMN变化的第一步。DMN内的功能连通性可能来自直接的解剖联系，间接的联系，或两者的某种组合。这项拨款的第一个总体目标是描绘mPFC和PMC子区域之间的直接和间接联系，以找到潜在的汇聚连接区域。此外，dMRI已经确定了精神疾病，包括重度抑郁症和成瘾，在白质通路中有特定的异常，可能与DMN结构相连。这些异常可能反映了特异性

DESCRIPTION (provided by applicant): The default mode network (DMN) is a set of brain regions consistently activated at rest and deactivated during task performance. DMN activity is abnormal in many neurological and psychiatric disorders, including major depressive disorder (MDD) and drug addiction. The two main parts of the DMN are the medial prefrontal cortex (mPFC) and posteromedial cortex (PMC), two areas that are spatially distant and have distinct canonical functions. While there is some evidence of direct connections between these general cortical areas, little is known about their specifics and how they link the network together as a whole. I hypothesize that the DMN is linked together by specific hub subareas that contain converging connections from multiple DMN regions, and the cingulum bundle and the internal capsule are the major connecting white matter bundles for this network. Thus, the goal of this proposal is to delineate how anatomical connections and pathways between mPFC and PMC allow them to operate as a network. Combining traditional anatomical techniques with diffusion magnetic resonance imaging (dMRI), I will determine the connections that underlie the DMN. Defining these specific DMN connections will establish the circuitry subserving neuroimaging results. This basic knowledge is fundamental and is the first step in understanding the changes in the DMN in disease. Functional connectivity within the DMN may result from direct anatomical links, indirect ones, or some combination of both. The first overall aim of this grant i to delineate the direct and indirect connections between subregions of the mPFC and PMC to find potential zones of converging connections. Furthermore, dMRI has identified psychiatric disorders, including MDD and addiction, with specific abnormalities within white matter pathways that likely link DMN structures. These abnormalities likely reflect disruption of specific connections. However, the fibers traveling through any given location within a white matter bundle remain unknown. The second and third aims are to establish white matter pathways that connect DMN structures using tracing and dMRI methods. This will link dMRI and anatomical tract-tracing, testing the validity of dMRI and providing a guide for how to interpret its results.