Parallel distributed networks resolved at high resolution reveal close juxtaposition of distinct regions
Parallel distributed networks resolved at high resolution reveal close juxtaposition of distinct regions
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DOI：
10.1152/jn.00808.2018
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发表时间：
2019-04-01
影响因子：
2.5
通讯作者：
Buckner, Randy L.
中科院分区：
文献类型：
--
作者：
Braga, Rodrigo M.;Van Dijk, Koene R. A.;Buckner, Randy L.
对个体内大规模分布式网络的检查揭示了群体平均研究中所缺少的皮质网络组织的细节。最近的一项发现是，分布式跨模态网络（通常称为“默认网络”）由两个紧密交错的网络组成，其中只有一个网络与后海马旁皮层耦合。并非所有针对个人的研究都确定了相同的网络，并且关于这两个网络的分离程度仍然存在疑问，特别是在假设为互连枢纽的区域内。在这项研究中，我们通过分析（基于种子的连接和分割）和数据投影（体积和表面）方法在两个个体中复制了网络分离的观察结果，每个个体扫描了 31 次。此外，还对三人进行了高分辨率（7T；1.35 毫米）功能磁共振成像检查，以进一步了解解剖细节。这两个网络的不同区域位于皮质带的相邻部分，有时位于同一沟内。先前被认为是枢纽的中线区域揭示了两个网络几乎完全的空间分离，在后扣带回和楔前叶中显示出复杂的空间地形。与海马旁皮层耦合的网络还揭示了直接位于海马内、下托处或附近的一个单独区域。这些集体结果支持默认网络由至少两个空间并置的网络组成。可以在个体中以高分辨率识别精细的空间细节和两个网络的并置，从而深入了解关联皮层的网络组织，并进一步限制对群体平均神经影像数据的解释。新的和值得注意的最近的证据表明，当在个体中定义时，规范的大规模网络（例如“默认网络”）会分解为并行分布式网络。这项研究使用高分辨率成像来表明，网络具有并置，有时在同一沟内和先前假设为网络枢纽的区域内很明显。在海马结构中，海马旁皮层和下托处或附近，也解决了一个网络的不同界限区域。
Examination of large-scale distributed networks within the individual reveals details of cortical network organization that are absent in group-averaged studies. One recent discovery is that a distributed transmodal network, often referred to as the "default network," comprises two closely interdigitated networks, only one of which is coupled to posterior parahippocampal cortex. Not all studies of individuals have identified the same networks, and questions remain about the degree to which the two networks are separate, particularly within regions hypothesized to be interconnected hubs. In this study we replicate the observation of network separation across analytical (seed-based connectivity and parcellation) and data projection (volume and surface) methods in two individuals each scanned 31 times. Additionally, three individuals were examined with high-resolution (7T; 1.35 mm) functional magnetic resonance imaging to gain further insight into the anatomical details. The two networks were identified with separate regions localized to adjacent portions of the cortical ribbon, sometimes inside the same sulcus. Midline regions previously implicated as hubs revealed near complete spatial separation of the two networks, displaying a complex spatial topography in the posterior cingulate and precuneus. The network coupled to parahippocampal cortex also revealed a separate region directly within the hippocampus, at or near the subiculum. These collective results support that the default network is composed of at least two spatially juxtaposed networks. Fine spatial details and juxtapositions of the two networks can be identified within individuals at high resolution, providing insight into the network organization of association cortex and placing further constraints on interpretation of group-averaged neuroimaging data.NEW & NOTEWORTHY Recent evidence has emerged that canonical large-scale networks such as the "default network" fractionate into parallel distributed networks when defined within individuals. This research uses high-resolution imaging to show that the networks possess juxtapositions sometimes evident inside the same sulcus and within regions that have been previously hypothesized to be network hubs. Distinct circumscribed regions of one network were also resolved in the hippocampal formation, at or near the parahippocampal cortex and subiculum.