Synchronization analysis between heart rate variability and EEG activity before, during, and after epileptic seizure

Area of Science:

• Neuroscience
• Cardiology
• Signal Processing

Background:

• Temporal lobe epilepsy (TLE) involves complex interactions between neurological and autonomic functions.
• Understanding heart rate variability (HRV) and electroencephalogram (EEG) synchronization offers insights into seizure dynamics.
• Previous research has not fully explored time-variant synchronization between HRV and EEG in TLE.

Purpose of the Study:

• To develop and apply a novel time-variant analysis for synchronization between HRV and EEG envelopes.
• To investigate HRV-EEG synchronization patterns in children with TLE, focusing on preictal and postictal periods.
• To explore potential lateralization of cardiac autonomic control in TLE based on HRV-EEG synchronization.

Main Methods:

• Artifact removal from EEG and computation of frequency band envelopes using the Hilbert transform.
• Quantification of synchronization between HRV and EEG envelopes via Morlet wavelet coherence.
• Statistical significance testing of time-variant coherences using an adapted surrogate data approach.

Main Results:

• Significant time-variant coherence was identified between the low-frequency HRV sub-band (0.08-0.12 Hz) and the EEG delta envelope (1.5-4 Hz).
• This synchronization was observed during both preictal and early postictal seizure phases.
• Synchronization was more pronounced in right hemispheric TLE patients compared to left hemispheric TLE patients.

Conclusions:

• The developed method effectively reveals time-variant synchronization between cardiac and brain activity in TLE.
• HRV-EEG synchronization patterns differ between left and right hemispheric TLE, suggesting lateralization.
• Findings support the hypothesis of right hemispheric lateralization of sympathetic cardiac control in TLE patients.