Validation of the flash-evoked response from fetal MEG

J McCubbin, P Murphy, H Eswaran, H Preissl, T Yee, S E Robinson, J Vrba
2007 Physics in Medicine and Biology  
Flash-evoked responses can be recorded from the fetus in utero. However, a standard analysis approach based on orthogonal projection (OP) to attenuate maternal and fetal cardiac signals leads to a spatial redistribution of the signal. This effect prevents the correlation of source location with a known fetal head location in some cases and the signal-to-noise ratio (SNR) is sometimes limited such that the response latency is difficult to determine. We used a modified beamformer model search
more » ... ysis to avoid the redistribution shortcoming and to improve the SNR. We included a statistical test for residual interference in the average and quantified significance of the evoked response with a bootstrap method. Selected source locations compared favorably to fetal head locations estimated from ultrasound exams. The evoked response time course was found to have a significant post-trigger peak with a latency between about 180 and 770 ms in more than 90% of the subject measurements. These results confirm that the combined application of a beamformer model search and bootstrap significance test provides a validation of the flash-evoked response observed in OP processed fetal MEG channels.
doi:10.1088/0031-9155/52/19/005 pmid:17881801 pmcid:PMC2600492 fatcat:3rlumkhntnfozntpinzsy3cgze