Darvas F, Pantazis D, Kucukaltun-Yildirim E, Leahy R M
Department of Electrical Engineering, Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089-2564, USA.
Neuroimage. 2004;23 Suppl 1:S289-99. doi: 10.1016/j.neuroimage.2004.07.014.
We survey the field of magnetoencephalography (MEG) and electroencephalography (EEG) source estimation. These modalities offer the potential for functional brain mapping with temporal resolution in the millisecond range. However, the limited number of spatial measurements and the ill-posedness of the inverse problem present significant limits to our ability to produce accurate spatial maps from these data without imposing major restrictions on the form of the inverse solution. Here we describe approaches to solving the forward problem of computing the mapping from putative inverse solutions into the data space. We then describe the inverse problem in terms of low dimensional solutions, based on the equivalent current dipole (ECD), and high dimensional solutions, in which images of neural activation are constrained to the cerebral cortex. We also address the issue of objective assessment of the relative performance of inverse procedures by the free-response receiver operating characteristic (FROC) curve. We conclude with a discussion of methods for assessing statistical significance of experimental results through use of the bootstrap for determining confidence regions in dipole-fitting methods, and random field (RF) and permutation methods for detecting significant activation in cortically constrained imaging studies.
我们综述了脑磁图（MEG）和脑电图（EEG）源估计领域。这些模态提供了以毫秒级时间分辨率进行功能性脑图谱绘制的潜力。然而，空间测量数量有限以及逆问题的不适定性对我们在不对逆解形式施加重大限制的情况下从这些数据生成准确空间图谱的能力构成了重大限制。在此，我们描述了用于解决将假定的逆解映射到数据空间的正向问题的方法。然后，我们根据基于等效电流偶极子（ECD）的低维解和神经激活图像被约束在大脑皮层的高维解来描述逆问题。我们还通过自由响应接收器操作特性（FROC）曲线解决了逆程序相对性能的客观评估问题。我们最后讨论了通过使用自助法确定偶极子拟合方法中的置信区域以及使用随机场（RF）和置换方法检测皮层约束成像研究中的显著激活来评估实验结果统计显著性的方法。
