The Pre-Interictal Network State in Idiopathic Generalized Epilepsies

Area of Science:

• Neuroscience
• Epileptology
• Computational Neuroscience

Background:

• Generalized spike wave discharges (GSWDs) are characteristic of Idiopathic Generalized Epilepsies (IGEs).
• Interictal and ictal GSWDs may arise from different pathogenetic mechanisms.
• Understanding the pre-ictal state is crucial for predicting GSWD generation.

Purpose of the Study:

• To investigate the functional brain network state preceding interictal GSWDs in IGEs.
• To analyze cortical connectivity patterns in the pre-ictal phase using high-density EEG.
• To identify network features and key brain regions involved in the pre-ictal state.

Main Methods:

• High-density electroencephalogram (HD-EEG) recording in 21 IGE patients.
• Functional connectivity analysis using lagged coherence and individual anatomy.
• Graph theory analysis to assess network properties (characteristic path length, clustering coefficient).

Main Results:

• Two distinct pre-ictal networks were identified, showing reversed connectivity attributes.
• A delta2 network (3-4 Hz) exhibited decreased characteristic path length and increased clustering.
• An alpha1 network (8-10.5 Hz) showed opposite trends, with involvement of DMN, DAN, VIS, and thalami.

Conclusions:

• The pre-ictal state in IGEs is characterized by the coupling of two distinct networks with specific connectivity patterns.
• This coupled network state may represent a favorable condition for the generation of interictal GSWDs.
• Findings provide insights into the neurophysiological mechanisms underlying GSWD formation in IGEs.