Principal component elimination method for the improvement of S/N in evoked neuromagnetic field measurements
Principal component elimination method for the improvement of S/N in evoked neuromagnetic field measurements
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DOI：
10.1109/10.775405
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发表时间：
1999-08-01
影响因子：
4.6
通讯作者：
Kuriki, S
中科院分区：
文献类型：
--
作者：
Kobayashi, T;Kuriki, S
在脑磁图的研究中，获得具有良好信噪比（S/N）且平均时间短的诱发场是非常重要的。噪声被认为主要是自发的神经磁场。在本研究中，我们提出了一种提高信噪比的方法。该方法的基本原理是消除多通道记录的神经磁场的主成分（PC），利用支配磁场的自发节律活动的同步特性。因此，提出的方法被称为主成分消去法（PCEM）。将PCEM应用于37通道超导量子干涉装置系统测量的神经磁场，叠加计算机产生的诱发场，以检验可能提高信噪比的可能性。研究发现，消除第一PC可以改善诱发场的SIN。与传统的简单平均相比，消除第一个PC后，信噪比的改善随着epoch数量的增加而增加，在平均超过128个epoch后达到50%以上。PCEM还将平均所需的epoch数量减少到传统简单平均所需的一半左右。
In the study of magnetoencephalography, it is important to obtain evoked fields with good signal-to-noise ratios (S/N) and with a small number of epochs in averaging. The noises are considered to be mainly spontaneous neuromagnetic fields. In the present study, we propose a method to improve the S/N. The basic principle of this method is the elimination of a principal component (PC) of multichannel-recorded neuromagnetic fields, utilizing the synchronized characteristics of spontaneous rhythmic activities dominating the fields. The proposed method is, therefore, called the principal component elimination method (PCEM). PCEM was applied to neuromagnetic fields measured by a 37-channel superconducting quantum interference device system, on which computer-generated evoked fields were superposed, in order to examine possible improvement in S/N. It was found that elimination of the first PC could improve the SIN of the evoked fields. The improvement in S/N with elimination of the first PC, compared to conventional simple averaging, increased with increases in the number of epochs and reached more than 50% after averaging over 128 epochs. PCEM also reduced the number of epochs needed in averaging to about half of that needed in conventional simple averaging.