Variability of EEG electrode positions and their underlying brain regions: Visualizing gel artifacts from a simultaneous EEG-fMRI dataset

Catriona L. Scrivener*, Arran T. Reader

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Introduction
We investigated the between-subject variability of EEG (electroencephalography) electrode placement from a simultaneously recorded EEG-fMRI (functional magnetic resonance imaging) dataset.

Methods
Neuro-navigation software was used to localize electrode positions, made possible by the gel artifacts present in the structural magnetic resonance images. To assess variation in the brain regions directly underneath electrodes we used MNI coordinates, their associated Brodmann areas, and labels from the Harvard-Oxford Cortical Atlas. We outline this relatively simple pipeline with accompanying analysis code.

Results

In a sample of 20 participants, the mean standard deviation of electrode placement was 3.94 mm in x, 5.55 mm in y, and 7.17 mm in z, with the largest variation in parietal and occipital electrodes. In addition, the brain regions covered by electrode pairs were not always consistent; for example, the mean location of electrode PO7 was mapped to BA18 (secondary visual cortex), whereas PO8 was closer to BA19 (visual association cortex). Further, electrode C1 was mapped to BA4 (primary motor cortex), whereas C2 was closer to BA6 (premotor cortex).

Conclusions
Overall, the results emphasize the variation in electrode positioning that can be found even in a fixed cap. This may be particularly important to consider when using EEG positioning systems to inform non-invasive neurostimulation.
Original languageEnglish
Article numbere2476
JournalBrain and Behavior
Volume12
Issue number2
Early online date18 Jan 2022
DOIs
Publication statusPublished - Feb 2022

Keywords / Materials (for Non-textual outputs)

  • EEG-fMRI
  • electrode positions
  • EEG cap
  • gel artifact
  • TMS neuro-navigation

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