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

ObjectiveTo 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.MethodsWe 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.ResultsActivity 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.ConclusionsDuring 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.SignificanceThe reproducibility of the magnetic SI and SII responses suggests clinical applicability of the presented MEG method.

► In 46 healthy newborns, activity from both the primary (SI) and secondary somatosensory cortices (SII) was detectable with magnetoencephalography to tactile stimulation of the contralateral index finger during quiet sleep (QS). ► No significant interhemispheric differences in the responses from SI or SII existed. ► Within the neonatal period [postmenstrual age (PMA) between 37 and 44 weeks] PMA, height, or gender did not significantly affect the latency or strength of the somatosensory evoked magnetic fields (SEFs).