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Effects of electrode density and electrolyte spreading in dense array electroencephalographic recording.
Lawrence L Greischar1, Cory A Burghy, Carien M van Reekum
1Department of Psychology, University of Wisconsin-Madison, Brogden Hall, Room 371, 1202 West Johnson Street, Madison, WI 53706, USA.
Summary
High-density electroencephalography (EEG) can reduce signal power due to electrolyte spreading between electrodes. Spherical spline interpolation effectively corrects these power decreases, improving high-density EEG data quality.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Signal Processing
Background:
- High-density electroencephalography (EEG) offers enhanced spatial resolution.
- Increased electrode density necessitates understanding its impact on measured potentials.
- Electrode spacing and electrolyte bridging can influence EEG signal characteristics.
Purpose of the Study:
- To investigate power differences in high-density EEG recordings as a function of electrode density and electrolyte spreading.
- To test a method for correcting power differences caused by electrolyte spreading.
Main Methods:
- EEG recordings were performed with varying electrode densities (6 vs. 128 electrodes).
- Hjorth electrical distances were computed to detect electrolyte spreading.
- Spherical spline interpolation was applied to correct power values at affected electrodes.
Main Results:
- Significant power decreases were observed in high-density EEG recordings compared to lower densities.
- Electrolyte spreading, indicated by Hjorth distances, predicted power decreases.
- Spherical spline interpolation successfully increased power values at affected electrodes.
Conclusions:
- Electrolyte spreading is a critical factor affecting power in high-density EEG.
- Scalp power maps and Hjorth distances can identify electrodes with electrolyte spreading.
- Spherical spline interpolation provides a viable correction method for high-density EEG data.