Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.

The development of new magnetic sensor technologies that promise sensitivities approaching that of conventional MEG technology while operating at far lower operating temperatures has catalysed the growing field of on-scalp MEG. The feasibility of on-scalp MEG has been demonstrated via benchmarking o...

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Main Authors: Lau M Andersen, Robert Oostenveld, Christoph Pfeiffer, Silvia Ruffieux, Veikko Jousmäki, Matti Hämäläinen, Justin F Schneiderman, Daniel Lundqvist
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2017-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC5524409?pdf=render
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spelling doaj-236ca791aec147c0b7f4603e6cd93a822020-11-25T01:20:09ZengPublic Library of Science (PLoS)PLoS ONE1932-62032017-01-01127e017860210.1371/journal.pone.0178602Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.Lau M AndersenRobert OostenveldChristoph PfeifferSilvia RuffieuxVeikko JousmäkiMatti HämäläinenJustin F SchneidermanDaniel LundqvistThe development of new magnetic sensor technologies that promise sensitivities approaching that of conventional MEG technology while operating at far lower operating temperatures has catalysed the growing field of on-scalp MEG. The feasibility of on-scalp MEG has been demonstrated via benchmarking of new sensor technologies performing neuromagnetic recordings in close proximity to the head surface against state-of-the-art in-helmet MEG sensor technology. However, earlier work has provided little information about how these two approaches compare, or about the reliability of observed differences. Herein, we present such a comparison, based on recordings of the N20m component of the somatosensory evoked field as elicited by electric median nerve stimulation. As expected from the proximity differences between the on-scalp and in-helmet sensors, the magnitude of the N20m activation as recorded with the on-scalp sensor was higher than that of the in-helmet sensors. The dipole pattern of the on-scalp recordings was also more spatially confined than that of the conventional recordings. Our results furthermore revealed unexpected temporal differences in the peak of the N20m component. An analysis protocol was therefore developed for assessing the reliability of this observed difference. We used this protocol to examine our findings in terms of differences in sensor sensitivity between the two types of MEG recordings. The measurements and subsequent analysis raised attention to the fact that great care has to be taken in measuring the field close to the zero-line crossing of the dipolar field, since it is heavily dependent on the orientation of sensors. Taken together, our findings provide reliable evidence that on-scalp and in-helmet sensors measure neural sources in mostly similar ways.http://europepmc.org/articles/PMC5524409?pdf=render
collection DOAJ
language English
format Article
sources DOAJ
author Lau M Andersen
Robert Oostenveld
Christoph Pfeiffer
Silvia Ruffieux
Veikko Jousmäki
Matti Hämäläinen
Justin F Schneiderman
Daniel Lundqvist
spellingShingle Lau M Andersen
Robert Oostenveld
Christoph Pfeiffer
Silvia Ruffieux
Veikko Jousmäki
Matti Hämäläinen
Justin F Schneiderman
Daniel Lundqvist
Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
PLoS ONE
author_facet Lau M Andersen
Robert Oostenveld
Christoph Pfeiffer
Silvia Ruffieux
Veikko Jousmäki
Matti Hämäläinen
Justin F Schneiderman
Daniel Lundqvist
author_sort Lau M Andersen
title Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
title_short Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
title_full Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
title_fullStr Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
title_full_unstemmed Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
title_sort similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2017-01-01
description The development of new magnetic sensor technologies that promise sensitivities approaching that of conventional MEG technology while operating at far lower operating temperatures has catalysed the growing field of on-scalp MEG. The feasibility of on-scalp MEG has been demonstrated via benchmarking of new sensor technologies performing neuromagnetic recordings in close proximity to the head surface against state-of-the-art in-helmet MEG sensor technology. However, earlier work has provided little information about how these two approaches compare, or about the reliability of observed differences. Herein, we present such a comparison, based on recordings of the N20m component of the somatosensory evoked field as elicited by electric median nerve stimulation. As expected from the proximity differences between the on-scalp and in-helmet sensors, the magnitude of the N20m activation as recorded with the on-scalp sensor was higher than that of the in-helmet sensors. The dipole pattern of the on-scalp recordings was also more spatially confined than that of the conventional recordings. Our results furthermore revealed unexpected temporal differences in the peak of the N20m component. An analysis protocol was therefore developed for assessing the reliability of this observed difference. We used this protocol to examine our findings in terms of differences in sensor sensitivity between the two types of MEG recordings. The measurements and subsequent analysis raised attention to the fact that great care has to be taken in measuring the field close to the zero-line crossing of the dipolar field, since it is heavily dependent on the orientation of sensors. Taken together, our findings provide reliable evidence that on-scalp and in-helmet sensors measure neural sources in mostly similar ways.
url http://europepmc.org/articles/PMC5524409?pdf=render
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