Epileptogenic Source Imaging Using Cross-Frequency Coupled Signals From Scalp EEG

Area of Science:

• Neuroscience
• Medical Imaging
• Signal Processing

Background:

• The epileptogenic zone (EZ) is crucial for seizure genesis and removal leads to seizure cessation.
• Accurate localization of the EZ is vital for successful epilepsy surgery.
• Current methods for EZ localization face challenges with signal noise and accuracy.

Purpose of the Study:

• To develop and validate a novel electroencephalography source imaging (ESI) method.
• To utilize cross-frequency coupled potential signals (S_CFC) derived from scalp EEG for improved EZ identification.
• To enhance the precision of intracranial electrode placement for epilepsy surgery.

Main Methods:

• Recorded scalp EEG from ten epilepsy patients (20 seizures).
• Constructed S_CFC from phase and amplitude of lower and higher frequency rhythms at seizure onset.
• Performed ESI using S_CFC and validated with computer modeling and resected brain regions.

Main Results:

• ESI successfully localized estimated sources within resected regions for high-frequency sampled seizures.
• S_CFC demonstrated superior noise performance compared to raw scalp EEG.
• Successful localization was achieved with a signal-to-noise ratio above 0.2, even with EMG artifacts.

Conclusions:

• Cross-frequency coupling is a neural network feature, not artifactual.
• The S_CFC method effectively extracts brain signals from noisy backgrounds.
• This ESI approach offers a promising tool for enhancing epilepsy surgery planning.