Conturo T E, Lori N F, Cull T S, Akbudak E, Snyder A Z, Shimony J S, McKinstry R C, Burton H, Raichle M E
Department of Radiology and Neuroimaging Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4525 Scott Avenue, St. Louis, MO 63110, USA.
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10422-7. doi: 10.1073/pnas.96.18.10422.
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.
正电子发射断层扫描和功能磁共振成像的功能成像彻底改变了对人类大脑的研究。然而，对脑系统组织的理解，尤其是用于认知的脑系统组织，仍然有限，因为目前还没有非侵入性追踪功能区域之间神经元连接的方法[克里克，F. & 琼斯，E.（1993年）《自然》（伦敦）361卷，第109 - 110页]。通过侵入性示踪技术在动物身上研究了详细的连接性，但这些侵入性研究无法在人类身上进行，而且动物实验结果也不能总是外推到人类系统。我们开发了用于活体人类的非侵入性神经元纤维追踪技术，利用磁共振成像表征水扩散的独特能力。我们通过从种子点网格追踪最快扩散方向（纤维方向）来重建整个大脑的纤维轨迹，然后选择连接解剖学或功能上（功能磁共振成像）定义区域的轨迹。我们通过胼胝体、膝状体 - 距状束和皮质下联合通路的例子展示了多种白质类别的纤维束扩散追踪。轨迹覆盖长距离，穿过分歧和紧密曲线，并在膝状体 - 距状束中表现出与动物示踪研究和人类视网膜拓扑研究一致的拓扑分离。此外，在其他通路中还揭示了以前未描述的拓扑结构。这种方法通过能够研究个体人类受试者中解剖学和功能定义的脑区之间的纤维连接，增强了现代成像的能力。
