Neonatal EEG at scalp is focal and implies high skull conductivity in realistic neonatal head models

Odabaee, Maryam, Tokariev, Anton, Layeghy, Siamak, Mesbah, Mostefa, Colditz, Paul B., Ramon, Ceon and Vanhatalo, Sampsa (2014) Neonatal EEG at scalp is focal and implies high skull conductivity in realistic neonatal head models. NeuroImage, 96 73-80. doi:10.1016/j.neuroimage.2014.04.007


Author Odabaee, Maryam
Tokariev, Anton
Layeghy, Siamak
Mesbah, Mostefa
Colditz, Paul B.
Ramon, Ceon
Vanhatalo, Sampsa
Title Neonatal EEG at scalp is focal and implies high skull conductivity in realistic neonatal head models
Journal name NeuroImage   Check publisher's open access policy
ISSN 1053-8119
1095-9572
Publication date 2014-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.neuroimage.2014.04.007
Volume 96
Start page 73
End page 80
Total pages 8
Place of publication Amsterdam, The Netherlands
Publisher Elsevier BV
Language eng
Abstract The potential improvements in spatial resolution of neonatal EEG used in source localization have been challenged by the insufficiencies in realistic neonatal head models. Our present study aimed at using empirical methods to indirectly estimate skull conductivity; the model parameter that is known to significantly affect the behavior of newborn scalp EEG and cause it to be markedly different from that of an adult. To this end, we used 64 channel EEG recordings to study the spatial specificity of scalp EEG by assessing the spatial decays in focal transients using both amplitudes and between-c'hannels linear correlations. The findings showed that these amplitudes and correlations decay within few centimeters from the reference channel/electrode, and that the nature of the decay is independent of the scalp area. This decay in newborn infants was found to be approximately three times faster than the corresponding decay in adult EEG analyzed from a set of 256 channel recordings. We then generated realistic head models using both finite and boundary element methods along with a manually segmented magnetic resonance images to study the spatial decays of scalp potentials produced by single dipole in the cortex. By comparing the spatial decays due to real and simulated EEG for different skull conductivities (from 0.003 to 0.3. S/m), we showed that a close match between the empirical and simulated decays was obtained when the selected skull conductivity for newborn was around 0.06-0.2. S/m. This is over an order of magnitude higher than the currently used values in adult head modeling. The results also showed that the neonatal scalp EEG is less smeared than that of an adult and this characteristic is the same across the entire scalp, including the fontanel region. These results indicate that a focal cortical activity is generally only registered by electrodes within few centimeters from the source. Hence, the conventional 10 to 20 channel neonatal EEG acquisition systems give a significantly spatially under sampled scalp EEG and may, consequently, give distorted pictures of focal brain activities. Such spatial specificity can only be reconciled by appreciating the anatomy of the neonatal head, especially the still unossified skull structure that needs to be modeled with higher conductivities than conventionally used in the adults.
Keyword Head model
High density EEG
Neonatal EEG
Source localization
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 2015 Collection
School of Medicine Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 9 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 27 May 2014, 10:14:38 EST by System User on behalf of Perinatal Research Centre