Spatial patterning of the neonatal EEG suggests a need for a high number of electrodes

Odabaee, Maryam, Freeman, Walter J., Colditz, Paul B., Ramon, Ceon and Vanhatalo, Sampsa (2013) Spatial patterning of the neonatal EEG suggests a need for a high number of electrodes. Neuroimage, 68 229-235. doi:10.1016/j.neuroimage.2012.11.062


Author Odabaee, Maryam
Freeman, Walter J.
Colditz, Paul B.
Ramon, Ceon
Vanhatalo, Sampsa
Title Spatial patterning of the neonatal EEG suggests a need for a high number of electrodes
Journal name Neuroimage   Check publisher's open access policy
ISSN 1053-8119
1095-9572
Publication date 2013-03-01
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.neuroimage.2012.11.062
Volume 68
Start page 229
End page 235
Total pages 7
Place of publication Amsterdam, The Netherlands
Publisher Elsevier
Language eng
Formatted abstract
There is an increasing demand for source analysis of neonatal EEG, but currently there is inadequate knowledge about i) the spatial patterning of neonatal scalp EEG and hence ii) the number of electrodes needed to capture neonatal EEG in full spatial detail. This study addresses these issues by using a very high density (2.5. mm interelectrode spacing) linear electrode array to assess the spatial power spectrum, by using a high density (64 electrodes) EEG cap to assess the spatial extent of the common oscillatory bouts in the neonatal EEG and by using a neonatal size spherical head model to assess the effects of source depth and skull conductivities on the spatial frequency spectrum. The linear array recordings show that the spatial power spectrum decays rapidly until about 0.5-0.8. cycles per centimeter. The dense array EEG recordings show that the amplitude of oscillatory events decays within 4-6. cm to the level of global background activity, and that the higher frequencies (12-20. Hz) show the most rapid spatial decline in amplitude. Simulation with spherical head model showed that realistic variation in skull conductivity and source depths can both introduce orders of magnitude difference in the spatial frequency of the scalp EEG. Calculation of spatial Nyquist frequencies from the spatial power spectra suggests that an interelectrode distance of about 6-10. mm would suffice to capture the full spatial texture of the raw EEG signal at the neonatal scalp without spatial aliasing or under-sampling. The spatial decay of oscillatory events suggests that a full representation of their spatial characteristics requires an interelectrode distance of 10-20. mm. The findings show that the conventional way of recording neonatal EEG with about 10 electrodes ignores most spatial EEG content, that increasing the electrode density is necessary to improve neonatal EEG source localization and information extraction, and that prospective source models will need to carefully consider the neonatally relevant ranges of tissue conductivities and source depths when source localizing cortical activity in neonates.
Keyword High resolution EEG
Source localization
Head model
Spatial spectrum
Spatial sampling
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: UQ Centre for Clinical Research Publications
Official 2014 Collection
School of Medicine Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 31 times in Thomson Reuters Web of Science Article | Citations
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