Jousmäki V, Hari R
Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
J Clin Neurophysiol. 1996 Mar;13(2):172-6. doi: 10.1097/00004691-199603000-00008.
We studied cardiac contamination of magnetoencephalographic signals in eight healthy volunteers. The signals were recorded in a magnetically shielded room while the subject was sitting under a whole-scalp neuromagnetometer and were averaged time-locked to the R wave of the electrocardiogram. The maximum amplitude of the cardiac artifact varied between the subjects and was on average 130 fT/cm. The number of significantly contaminated channels was higher over the left than the right hemisphere. The electric and magnetic signals varied over time in the same way, implying that the artifacts are generated by cardiac currents, without any significant contribution from blood-flow-related pulsations or body movements. These artifacts may have a considerable effect on unaveraged data, i.e., recordings of spontaneous brain activity, and thus should be taken into account in the analysis.
我们研究了8名健康志愿者的脑磁图信号的心脏污染情况。信号在磁屏蔽室内记录，受试者坐在全头型神经磁强计下，并与心电图的R波进行时间锁定平均。心脏伪迹的最大幅度在受试者之间有所不同，平均为130 fT/cm。显著受污染通道的数量在左半球比右半球更多。电信号和磁信号随时间以相同方式变化，这意味着伪迹是由心脏电流产生的，与血流相关的脉动或身体运动没有任何显著贡献。这些伪迹可能对未平均的数据（即自发脑活动记录）有相当大的影响，因此在分析中应予以考虑。
