Tangential derivative mapping of axial MEG applied to event-related desynchronization research
Tangential derivative mapping of axial MEG applied to event-related desynchronization research
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DOI：
10.1016/s1388-2457(00)00272-8
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发表时间：
2000-07-01
影响因子：
4.7
通讯作者：
Knösche, TR
中科院分区：
文献类型：
--
作者：
Bastiaansen, MCM;Knösche, TR
目标：使用轴向梯度计记录的 MEG 数据的地形图的一个问题是，场极值是在位于神经元发生器两侧的传感器处测量的，而不是在源正上方的传感器处测量的。这对于 MEG 数据上的事件相关去同步化 (ERD) 的计算是有问题的，因为 ERD 依赖于信号最大值和神经元发生器位置之间的对应关系。 方法：我们提出了一种基于计算 MEG 数据的空间导数的新方法。通过正向仿真研究了该方法的局限性，并将该方法应用于150通道的MEG数据集。结果：仿真表明该方法存在一定的局限性。 (1) 较少的通道会降低精度和幅度。 (2)不太适合深度或非常广泛的源。 (3) 多个源只有在彼此距离不太近的情况下才能区分。将该方法应用于实验数据的 ERD 计算中，使得 ERD 图谱有了相当大的改进。结论：无论是对于 MEG 的地形图还是通过 ERD 分析节律性 MEG 活性，所提出的方法都比原始 MEG 信号具有显着的优势。 (C) 2000 Elsevier Science Ireland Ltd. 保留所有权利。
Objectives: A problem with the topographic mapping of MEG data recorded with axial gradiometers is that field extrema are measured at sensors located at either side of a neuronal generator instead of at sensors directly above the source. This is problematic for the computation of event-related desynchronization (ERD) on MEG data, since ERD relies on a correspondence between the signal maximum and the location of the neuronal generator.Methods: We present a new method based on computing spatial derivatives of the MEG data. The limitations of this method were investigated by means of forward simulations, and the method was applied to a 150-channel MEG dataset.Results: The simulations showed that the method has some limitations. (1) Fewer channels reduce accuracy and amplitude. (2) It is less suitable for deep or very extended sources. (3) Multiple sources can only be distinguished if they are not too close to each other. Applying the method in the calculation of ERD on experimental data led to a considerable improvement of the ERD maps.Conclusions: The proposed method offers a significant advantage over raw MEG signals, both for the topographic mapping of MEG and far the analysis of rhythmic MEG activity by means of ERD. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.