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Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Altered EEG microstate dynamics reflect depressive symptoms in temporal lobe epilepsy
Krikor Bornazyan1, Linda S Oh1, Victoria Ho2
1Department of Neurology, University of California, Irvine, Orange, CA 92868, USA.
Epilepsy & Behavior : E&B
|July 18, 2026
Summary
Depressive symptoms in temporal lobe epilepsy (TLE) are linked to altered brain activity patterns. Specifically, EEG microstate dynamics show increased temporal rigidity in the ictal hemisphere-aligned state, reflecting impaired network flexibility.
Area of Science:
- Neuroscience
- Epileptology
- Psychiatry
Background:
- Depressive symptoms are a common comorbidity in temporal lobe epilepsy (TLE).
- Neural mechanisms linking seizure networks to affective symptoms are unclear.
- Limbic network dysfunction is implicated in both epilepsy and depression.
Purpose of the Study:
- To investigate if electroencephalography (EEG) microstate dynamics reflect depressive symptom severity in TLE.
- To examine network alterations associated with depressive symptoms in individuals with unilateral TLE.
Main Methods:
- Analysis of resting-state scalp EEG from 26 individuals with unilateral TLE.
- Identification of EEG microstates by clustering global field power peaks.
- Quantification of microstate parameters (dwell time, fractional occupancy, transition entropy) and correlation with Beck Depression Inventory-II (BDI) scores.
Main Results:
- Individuals with high depressive symptoms (BDI ≥ 13) showed longer dwell time in the ictal hemisphere-aligned microstate.
- Dwell time in this microstate correlated significantly with depressive symptom severity (r = 0.57, p = 0.002).
- Higher depressive symptoms were associated with reduced global transition entropy (p = 0.02), indicating decreased microstate transition flexibility.
Conclusions:
- Increased temporal rigidity of the ictal hemisphere-aligned brain microstate is associated with higher depressive symptom burden in TLE.
- This rigidity reflects impaired disengagement of epileptogenic network configurations.
- Depressive symptoms in TLE may stem from epilepsy-related disruptions in large-scale neural dynamics.
