title: Validation of the flash-evoked response from fetal MEG.
abstract: 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 analysis 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.
authors: Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors: J
authors: J
authors: McCubbin
authors: P
authors: P
authors: Murphy
authors: H
authors: H
authors: Eswaran
authors: H
authors: H
authors: Preissl
authors: T
authors: T
authors: Yee
authors: S E
authors: SE
authors: Robinson
authors: J
authors: J
authors: Vrba
mesh_terms: D000465:Algorithms; D001921:Brain / Q000196:embryology* / Q000502:physiology*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005323:Fetal Monitoring / Q000379:methods*; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D010775:Photic Stimulation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity