Is ocular voltage propagation to the electroencephalogram frequency dependent?

Area of Science:

• Neuroscience
• Biomedical Engineering
• Signal Processing

Background:

• Electroencephalogram (EEG) signals are often contaminated by electrooculogram (EOG) artifacts from eye movements and blinks.
• Conventional methods use propagation coefficients (Bs) to subtract EOG from EEG.
• The frequency domain approach (FDA) uses frequency-dependent Bs, while the time domain approach (TDA) uses frequency-independent Bs.

Purpose of the Study:

• To investigate whether propagation coefficients (Bs) for eye movement artifacts in EEG are frequency-dependent.
• To compare the suitability of the frequency domain approach (FDA) versus the time domain approach (TDA) for EOG artifact correction in EEG.

Main Methods:

• Recorded 20-minute EEG and EOG data from 24 participants during eye movement and blink tasks.
• Calculated propagation coefficients (Bs) for eye movement event-related potentials (ERPs) across frequency bands (0-40 Hz).
• Analyzed Bs at varying signal-to-noise ratios and compared across frequency bands and EOG types (vertical/horizontal).

Main Results:

• At high signal-to-noise ratios, eye movement propagation coefficients (Bs) showed no significant differences across tested frequency bands for both vertical and horizontal EOG.
• Minor differences observed in blink Bs across frequency bands were within the margin of error.
• No significant frequency dependency was found for eye movement artifact correction coefficients.

Conclusions:

• The time domain approach (TDA), using frequency-independent propagation coefficients (Bs), may be more appropriate for correcting eye movement artifacts in EEG compared to the frequency domain approach (FDA).
• This finding simplifies artifact correction strategies in EEG analysis, particularly in high signal-to-noise conditions.