Canonical source reconstruction for MEG.
Canonical source reconstruction for MEG.
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DOI：
10.1155/2007/67613
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发表时间：
2007
影响因子：
--
通讯作者：
Friston KJ
中科院分区：
文献类型：
--
作者：
Mattout J;Henson RN;Friston KJ
我们描述了一种简单而有效的解决方案，用于将电磁源重建为规范或标准的解剖空间。它的简单性在于将特定对象的解剖学结合到正向模型中，从而避免了皮质表面提取的需要。正向模型从标准立体定向空间中定义的规范大脑皮层网格开始。网格以一种非线性的方式扭曲，以匹配受试者的解剖结构。这种扭曲是从受试者的结构MRI图像的空间归一化得到的变换的逆，使用已经为其他成像方式建立的全自动程序。使用翘曲网格结合球形头部模型(不依赖于个体解剖结构)来计算电磁铅场。随后的正向模型是使用经验贝叶斯方案进行倒置的，我们在之前的几篇文章中已经描述过这种方案。关键是，因为解剖学信息进入正向模型，所以不需要对重建的源活动进行空间归一化。换句话说，构成网格的每个来源在标准的立体定向空间内都有预定的和唯一的解剖属性。这使得能够汇集来自多个受试者的数据并在立体定向坐标中报告结果。此外，它允许在同一解剖框架内优雅地融合功能磁共振成像和脑磁图数据。
We describe a simple and efficient solution to the problem of reconstructing electromagnetic sources into a canonical or standard anatomical space. Its simplicity rests upon incorporating subject-specific anatomy into the forward model in a way that eschews the need for cortical surface extraction. The forward model starts with a canonical cortical mesh, defined in a standard stereotactic space. The mesh is warped, in a nonlinear fashion, to match the subject's anatomy. This warping is the inverse of the transformation derived from spatial normalization of the subject's structural MRI image, using fully automated procedures that have been established for other imaging modalities. Electromagnetic lead fields are computed using the warped mesh, in conjunction with a spherical head model (which does not rely on individual anatomy). The ensuing forward model is inverted using an empirical Bayesian scheme that we have described previously in several publications. Critically, because anatomical information enters the forward model, there is no need to spatially normalize the reconstructed source activity. In other words, each source, comprising the mesh, has a predetermined and unique anatomical attribution within standard stereotactic space. This enables the pooling of data from multiple subjects and the reporting of results in stereotactic coordinates. Furthermore, it allows the graceful fusion of fMRI and MEG data within the same anatomical framework.