Macroscale intrinsic dynamics are associated with microcircuit function in focal and generalized epilepsies

Area of Science:

• Neuroscience
• Systems Biology
• Medical Imaging

Background:

• Epilepsies are neurological disorders marked by abnormal brain activity and altered functional organization across multiple scales.
• The precise impact of epilepsy on macroscale intrinsic dynamics and microcircuit organization remains unclear.
• Understanding these changes is crucial for their pathological relevance.

Purpose of the Study:

• To investigate differences in macroscale intrinsic dynamics and microcircuit organization in epilepsy.
• To explore the links between macroscale and microscale alterations in epilepsy.
• To determine how temporal lobe epilepsy (TLE) and genetic generalized epilepsy with tonic-clonic seizure (GTCS) differ in these aspects.

Main Methods:

• Collected fMRI BOLD time-series data from patients with TLE, GTCS, and healthy controls.
• Extracted temporal features to characterize macroscale intrinsic dynamics.
• Simulated microcircuit neuronal dynamics using a large-scale biological model.

Main Results:

• Significant differences in macroscale time-series features were observed in primary and default mode networks in both TLE and GTCS.
• Biophysical simulations showed reduced recurrent connections in somatomotor microcircuits, more pronounced in GTCS.
• Strong spatial correlations were found between macroscale dynamics and microcircuit dysfunction in epilepsies.

Conclusions:

• Epilepsy causes systematic abnormalities in the brain's hierarchical organization.
• Abnormal neuronal activity impacts both primary and high-order brain networks.
• Findings highlight the interplay between macroscale and microscale disruptions in epilepsy.