Abstracts

Rationale: The aim of this study was to explore the immediate changes of the hippocampus and amygdala functional connectivity (FC) when interictal epileptiform discharges (IEDs) occurred in unilateral temporal lobe epilepsy (TLE). Methods: Patients with unilateral TLE were recruited and underwent EEG-fMRI scanning. Simultaneous EEG was used to define the pre-spike (10 seconds before spike) and post-spike (10 seconds after spike) periods. The left/right hippocampus/amygdala separately being the seeds, dynamic functional connectivity analysis was applied to map the network alterations throughout the peri-IED periods. Results: A total of 269 IED events (137 left, 132 right) from 21 unilateral TLE patients (10 left, 11 right) were analyzed. The results showed that left IEDs had a greater influence on the hippocampus-seeded networks, whereas right IEDs affected the amygdala-seeded networks more. IEDs, predominantly the left ones, disconnected the ipsilateral hippocampus and components of the default mode network, which might have influence on cognitive function. Left IEDs weakened the FC between the left hippocampus/amygdala and the reward-emotion network (more of the prefrontal-limbic system), which might disturb emotion regulation. Other networks including the executive control network and visual network also showed altered FC throughout left IEDs. Coactivation of the reward-emotion network (more of the reward system) was observed after right IEDs, possibly indicating one of the mechanisms for forced normalization. Conclusions: This study directly linked the disrupted functional networks in TLE to epileptiform activities and offered a unique point of view for understanding the mechanisms of comorbidities in TLE. Funding: This study was supported by the National Natural Science foundation of China (NSFC Grants No. 81401079, 81771402, 81420108014, 81401076 and 81601133).