Methods for examining electrophysiological coherence in epileptic networks.

Area of Science:

• Neuroscience
• Epilepsy Research
• Brain Network Analysis

Background:

• Epilepsy involves focal brain abnormalities and seizure propagation through cerebral networks.
• Understanding pathological network engagement is crucial for epilepsy diagnosis and treatment.
• Dense array electroencephalography (dEEG) offers high-density scalp recordings for epilepsy investigation.

Purpose of the Study:

• To investigate pathological network engagement in epilepsy using dEEG and source analysis.
• To identify characteristic coherence patterns associated with epileptiform discharges.
• To evaluate the utility of dEEG in localizing seizure onset zones.

Main Methods:

• Utilized dense array electroencephalography (dEEG) in five epilepsy patients.
• Performed individual electrical head modeling, MRI registration, and cortical surface extraction.
• Applied inverse source estimation and computed spectral coherence among brain regions (1-70 Hz).

Main Results:

• Identified distinct source coherence patterns during pre-spike, spike, and post-spike intervals.
• Observed localized abnormal coherence in the temporal lobe of one patient with focal epilepsy.
• Found characteristic coherence patterns in other patients, suggesting network synchronization but not always unequivocal epileptogenic zones.

Conclusions:

• dEEG-based source analysis can reveal characteristic network coherence patterns in epilepsy.
• While localized abnormalities were seen in one case, network synchronization was evident in others.
• Non-invasive dEEG localization of seizure onset correlated with intracranial EEG and surgical outcomes.