Evoked magnetic fields from primary and secondary somatosensory cortices: A reliable tool for assessment of cortical processing in the neontal period

Objective: To determine interhemispheric differences and effect of postmenstrual age (PMA), height, and gender on somatosensory evoked magnetic fields (SEFs) from the primary (SI) and secondary (SII) somatosensory cortices in healthy newborns.
Methods: We recorded SEFs to stimulation of the contralateral index finger (right in 46 and left in 12) healthy fullterm newborns and analyzed the magnetic responses with equivalent current dipoles.
Results: Activity from both the SI and SII was consistently detectable in the contralateral hemisphere of the newborns during quiet sleep. No significant interhemispheric differences existed in SI or SII response peak latencies, source strengths, or location (n = 8, quiet sleep). SI or SII response peak latency or source strength were not significantly affected by PMA, height, or gender.
Conclusions: During the neonatal period (PMA 37–44 weeks), activity from the contralateral SI and SII can be reliably evaluated with MEG. The somatosensory responses are similar in the left and right hemispheres and no corrections for exact PMA, height, or gender are necessary for interpreting the results.
However, the evaluation should be conducted in quiet sleep.
Significance: The reproducibility of the magnetic SI and SII responses suggests clinical applicability of the presented MEG method.
2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights
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