Patterns of altered functional connectivity in mesial temporal lobe epilepsy

Area of Science:

• Neuroscience
• Epileptology
• Functional Neuroimaging

Background:

• Mesial temporal lobe epilepsy (MTLE) affects cognitive and psychiatric functions beyond the primary seizure focus.
• Functional connectivity analysis using BOLD signals reveals intrinsic brain networks.
• Resting-state functional connectivity (rsFC) is a key method for studying brain network alterations in neurological disorders.

Purpose of the Study:

• To compare interictal functional connectivity in MTLE patients with healthy controls.
• To identify specific brain regions with altered functional connectivity in MTLE.
• To investigate the relationship between functional connectivity changes and clinical impairments in MTLE.

Main Methods:

• Utilized resting-state electroencephalography-functional magnetic resonance imaging (EEG-fMRI) data from 16 right and 7 left MTLE patients and 23 healthy controls.
• Defined volumes of interest (VOIs) in the bilateral amygdala and hippocampus (LA, RA, LH, RH).
• Analyzed group differences in BOLD signal correlations between VOIs and other brain regions.

Main Results:

• Right MTLE patients showed decreased connectivity between the right amygdala/hippocampus and default mode network (DMN), limbic prefrontal, and contralateral mesial temporal regions.
• Left MTLE patients exhibited reduced connectivity between the left amygdala/hippocampus and DMN, contralateral hippocampus, and bilateral limbic prefrontal regions.
• Both patient groups displayed altered connectivity patterns involving the amygdala, hippocampus, DMN, and limbic structures.

Conclusions:

• Unilateral MTLE is associated with reduced functional connectivity of the amygdala and hippocampus, bilaterally.
• These connectivity deficits extend to the default mode network (DMN) and dopaminergic mesolimbic pathways.
• Altered functional connectivity may underlie the cognitive and psychiatric comorbidities common in MTLE patients.