Disrupted causal connectivity in mesial temporal lobe epilepsy.

Area of Science:

• Neuroscience
• Epileptology
• Systems Neuroscience

Background:

• Mesial temporal lobe epilepsy (mTLE) involves pathological changes in the temporal lobe.
• Functional alterations extend beyond the temporal lobe to extratemporal regions.
• Understanding information flow between the epileptogenic zone (EZ) and other brain areas is crucial.

Purpose of the Study:

• To investigate the information flow between the epileptogenic zone (EZ) and other brain regions in patients with left mTLE.
• To identify alterations in causal interactions between the EZ and widespread brain networks.

Main Methods:

• Resting-state functional magnetic resonance imaging (RS-fMRI) data from 23 left mTLE patients and matched controls.
• Identification of the potential EZ using amplitude of low-frequency fluctuation (ALFF).
• Voxel-wise Granger causality analysis to assess information flow between the EZ and the whole brain.

Main Results:

• Patients showed decreased EZ to thalamus/basal ganglia driving effects and increased feedback.
• Altered causal relationships were observed between the EZ and cortical networks (default mode, limbic, visual, executive control).
• EZ influence on specific regions correlated with disease duration; feedback to EZ correlated with disease progression.

Conclusions:

• mTLE is associated with widespread abnormal functional interactions between the EZ and other brain regions.
• Epileptic activity initiation may depend on both the EZ and large-scale brain network activity.
• Causal topological organization is disrupted in mTLE, offering insights into its pathophysiology.