Assessment of subcortical source localization using deep brain activity imaging model with minimum norm operators: a MEG study.
Assessment of subcortical source localization using deep brain activity imaging model with minimum norm operators: a MEG study.
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DOI：
10.1371/journal.pone.0059856
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Schwartz D
中科院分区：
文献类型：
--
作者：
Attal Y;Schwartz D
皮质下结构参与许多健康和病理性脑过程。脑磁图（magnetoencephalography，MEG）是脑电研究的重要工具。本研究的目的是评估源定位的准确性，并比较在皮层下发电机的特定情况下，三个逆算子的特性。脑磁图对皮层下源的敏感性较低，主要是因为它们与传感器的距离和它们复杂的细胞结构。然而，我们表明，使用一个现实的解剖和电生理模型的深部脑活动（DBA），来源作出可测量的贡献MEG传感器信号。此外，我们研究的点扩散和串扰功能的wMNE，sLORETA和dSPM逆运算符，以表征在皮层和皮层下区域的失真，并研究如何噪声归一化方法可以提高或偏差的准确性。然后，我们运行Monte Carlo模拟与新皮层和皮层下激活。在单一海马斑片激活的情况下，结果表明，脑磁图确实可以定位在头部和海马体的发电机具有良好的准确性。然后，我们处理的问题，同时皮层和皮层下激活。wMNE可以检测嵌入在具有小于其两倍的幅度的皮层激活中的海马激活，但它不能完全纠正对更表面来源的偏差。dSPM和sLORETA仍然可以检测到高于该阈值的海马活动，但这种检测可能包括产生更深的幽灵源。最后，使用DBA模型，我们表明，检测正在进行的大脑活动的弱丘脑调制是可能的。
Subcortical structures are involved in many healthy and pathological brain processes. It is crucial for many studies to use magnetoencephalography (MEG) to assess the ability to detect subcortical generators. This study aims to assess the source localization accuracy and to compare the characteristics of three inverse operators in the specific case of subcortical generators. MEG has a low sensitivity to subcortical sources mainly because of their distance from sensors and their complex cyto-architecture. However, we show that using a realistic anatomical and electrophysiological model of deep brain activity (DBA), the sources make measurable contributions to MEG sensors signals. Furthermore, we study the point-spread and cross-talk functions of the wMNE, sLORETA and dSPM inverse operators to characterize distortions in cortical and subcortical regions and to study how noise-normalization methods can improve or bias accuracy. We then run Monte Carlo simulations with neocortical and subcortical activations. In the case of single hippocampus patch activations, the results indicate that MEG can indeed localize the generators in the head and the body of the hippocampus with good accuracy. We then tackle the question of simultaneous cortical and subcortical activations. wMNE can detect hippocampal activations that are embedded in cortical activations that have less than double their amplitude, but it does not completely correct the bias to more superficial sources. dSPM and sLORETA can still detect hippocampal activity above this threshold, but such detection might include the creation of ghost deeper sources. Finally, using the DBA model, we showed that the detection of weak thalamic modulations of ongoing brain activity is possible.
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