Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: a partial directed coherence study

Area of Science:

• Neuroscience
• Epilepsy Research
• Brain Connectivity

Background:

• Photosensitive epilepsy (PSE) is a common reflex epilepsy triggered by visual stimuli.
• Intermittent photic stimulation (IPS) elicits electroencephalography (EEG) paroxysms in PSE.
• Understanding dynamic neuronal network changes during epileptic discharge onset is crucial.

Purpose of the Study:

• To investigate dynamic changes in EEG connectivity patterns in photosensitive (PS) epilepsy patients.
• To compare connectivity during resting state and during intermittent photic stimulation (IPS).
• To identify neuronal network alterations preceding and during EEG epileptic discharges.

Main Methods:

• EEG signals analyzed in 10 PS patients and 10 controls under resting and IPS conditions.
• Partial Directed Coherence (PDC) used to assess effective connectivity.
• Analysis focused on anterior-posterior and interhemispheric connectivity in beta and gamma bands.

Main Results:

• PS patients showed enhanced EEG connectivity (increased number and strength of connections).
• Increased connectivity was observed in the beta band at rest and gamma band during IPS.
• Hyperconnectivity predominantly involved anterior cortical regions in PS patients, both at rest and during IPS.

Conclusions:

• PS patients exhibit abnormal EEG hyperconnectivity, particularly in anterior cortical regions.
• This anterior hyperconnectivity is present both at rest and during IPS.
• Anterior cortical areas play a significant role in generating hypersynchronization leading to IPS-induced epileptic discharges.