Koch Martin A, Norris David G, Hund-Georgiadis Margret
Max Planck Institute of Cognitive Neuroscience, Stephanstrasse 1a, D-04103 Leipzig, Germany.
Neuroimage. 2002 May;16(1):241-50. doi: 10.1006/nimg.2001.1052.
This article examines functional and anatomical connectivity in healthy human subjects measured with magnetic resonance imaging methods. Anatomical connectivity in white matter is obtained from measurements of the diffusion tensor. A Monte-Carlo simulation determines the probability that a particle diffuses between two points, with the probability of a jump in a particular direction from a given voxel being based on the local value of the diffusion tensor components. Functional connectivity between grey matter pixels is assessed without recourse to a specific activation paradigm, by calculating the correlation coefficient between random fluctuations in the blood oxygenation level-dependent signal time course in different pixels. The methods are used to examine the anatomical and functional connectivities between crowns of adjacent gyri. A high functional connectivity was found between grey matter pixels, with white matter displaying only very low correlation. A comparison of the measurements of anatomical and functional connectivity found that there is no simple correlation between these measures, except that low values of functional connectivity were not found together with high values of anatomical connectivity. Furthermore pairs of regions situated around the central sulcus indicated a dependence of the two connectivity measures on each other. These results are in accordance with an interpretation that regions which are clearly directly linked by white matter fiber tracts should show high functional connectivity, but that the inverse need not be true as functional connectivity may also be indirectly mediated via more distant grey matter regions.
本文研究了用磁共振成像方法测量的健康人类受试者的功能连接性和解剖连接性。白质中的解剖连接性通过扩散张量测量获得。蒙特卡罗模拟确定粒子在两点之间扩散的概率，从给定体素向特定方向跳跃的概率基于扩散张量分量的局部值。通过计算不同像素中血氧水平依赖信号时间过程的随机波动之间的相关系数，在不依赖特定激活范式的情况下评估灰质像素之间的功能连接性。这些方法用于检查相邻脑回顶部之间的解剖和功能连接性。发现灰质像素之间存在高功能连接性，而白质仅显示出非常低的相关性。解剖连接性和功能连接性测量结果的比较发现，这些测量之间不存在简单的相关性，只是功能连接性低值与解剖连接性高值不会同时出现。此外，位于中央沟周围的区域对表明两种连接性测量相互依赖。这些结果符合这样一种解释，即由白质纤维束明显直接相连的区域应显示出高功能连接性，但反之不一定成立，因为功能连接性也可能通过更远的灰质区域间接介导。
