Tracking neuronal fiber pathways in the living human brain
Tracking neuronal fiber pathways in the living human brain
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DOI：
10.1073/pnas.96.18.10422
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发表时间：
1999-08-31
影响因子：
11.1
通讯作者：
Raichle, ME
中科院分区：
文献类型：
--
作者：
Conturo, TE;Lori, NF;Raichle, ME
正电子发射断层扫描和功能性核磁共振成像的功能成像已经彻底改变了人类大脑的研究。然而，对大脑系统的组织，特别是那些用于认知的组织的理解仍然有限，因为目前没有方法可以对功能区域之间的神经元连接进行无创跟踪[:Crick， F & Jones， E, (1993) Nature (London) 361, 109-110]。通过侵入性示踪技术已经在动物身上研究了详细的连接，但这些侵入性研究不能在人类身上进行，而且动物的结果也不能总是推断到人类系统。我们已经开发了用于活体的非侵入性神经元纤维跟踪，利用MRI表征水扩散的独特能力，我们通过跟踪种子点网格中最快扩散的方向（纤维方向）来重建整个大脑的纤维轨迹，然后选择连接解剖或功能（功能性MRI）定义区域的轨迹。我们以胼胝体、膝骨骼肌和皮层下相关通路为例，展示了多种白质中纤维束的扩散跟踪，这些跟踪覆盖了长距离，通过分叉和紧密曲线进行导航，并且在膝骨骼肌束中表现出拓扑分离，与动物示踪剂研究和人类视网膜切除研究一致。此外，先前未描述的拓扑结构在其他途径中被揭示。这种方法通过研究个体受试者在解剖学和功能上定义的大脑区域之间的纤维连接，增强了现代成像的能力。
Functional imaging with positron emission tomography and functional MRI has revolutionized studies of the human brain. Understanding the organization of brain systems, especially those used for cognition, remains limited, however, because no methods currently exist for noninvasive tracking of neuronal connections between functional regions [:Crick, F & Jones, E, (1993) Nature (London) 361, 109-110]. Detailed connectivities have been studied in animals through invasive tracer techniques, but these invasive studies cannot be done in humans, and animal results cannot always be extrapolated to human systems. We have developed noninvasive neuronal fiber tracking for use in living humans, utilizing the unique ability of MRI to characterize water diffusion, We reconstructed fiber trajectories throughout the brain by tracking the direction of fastest diffusion (the fiber direction) from a grid of seed points, and then selected tracks that join anatomically or functionally (functional MRI) defined regions. We demonstrate diffusion tracking of fiber bundles in a variety of white matter classes with examples in the corpus callosum, geniculo-calcarine, and subcortical association pathways, Tracks covered long distances, navigated through divergences and tight curves, and manifested topological separations in the geniculo-calcarine tract consistent with tracer studies in animals and retinotopy studies in humans. Additionally, previously undescribed topologies were revealed in the other pathways. This approach enhances the power of modern imaging by enabling study of fiber connections among anatomically and functionally defined brain regions in individual human subjects.