Temporal Lobe Epilepsy Perturbs the Brain-Wide Excitation-Inhibition Balance: Associations with Microcircuit...

Area of Science:

• Neuroscience
• Epileptology
• Computational Psychiatry

Background:

• Excitation-inhibition (E/I) imbalance is a key hypothesis in epilepsy pathophysiology.
• Research has primarily focused on cellular mechanisms, leaving macroscale E/I dynamics and clinical relevance underexplored.

Purpose of the Study:

• To investigate macroscale E/I imbalance in epilepsy using the Hurst exponent from resting-state fMRI.
• To explore microcircuit mechanisms and clinical significance of E/I imbalance in temporal lobe epilepsy (TLE).

Main Methods:

• Computed Hurst exponent from resting-state fMRI time series as an index of the E/I ratio.
• Utilized biophysical models to simulate microcircuit parameters.
• Employed connectome decoders and analyzed cross-sectional and longitudinal patient data.

Main Results:

• Observed a decreased Hurst exponent in pharmaco-resistant TLE, indicating increased network excitability.
• Identified temporolimbic and frontocentral cortices as potential epicenters of E/I imbalance.
• Found correlations between E/I ratio elevation and disease duration, seizure frequency, epileptic spikes, and cognitive decline.

Conclusions:

• Provides in vivo evidence for a macroscale shift in E/I balance in TLE patients.
• Suggests progressive functional imbalances contribute to cognitive decline in epilepsy.
• Hurst exponent-based classification achieved high accuracy in distinguishing TLE patients from healthy controls.