Frequency-dependent Alterations Of Neural Networks During Interictal Periods In Childhood Absence Epilepsy

Objective:Childhood absence epilepsy(CAE)is a common benign childhood-onset syndrome with high cure rate.However,the neuropsychological deficits have been determined as long-term consequences of absence seizures by recent relative studies,which imply abnormal neural networks in the inter-ictal periods.The aim of this study was to investigate whether the neural networks of patients with CAE are altered during the inter-ictal periods in comparison with healthy controls,using multi-frequency magnetoencephalography(MEG)data.Methods:MEG data from 13 untreated CAE patients and 10 healthy controls were recorded with a whole-head CTF MEG system with 275 channels.The sampling rate was 6000 Hz,and all data were filtered with band-pass filters at eight pre-defined bandwidths.First,we computed the volumetric sources of activity in the entire brain by a two-step beam-forming method.Then,correlation analysis and Granger causality analysis were used to construct an effective connectivity(EC)network at the source level.Alterations in the spatial pattern and topography of the neural network,characterized by clustering coefficient,path length,degree and connectivity strength,in CAE were investigated by comparing the patients with the controls.Especially,we chose the precuneus/posterior cingulate cortex(PC/PCC)as a region of interest(ROI)to compare the EC networks involving the ROI between the two groups.Results:The network pattern was altered mainly in 1-4 Hz,showing a strong connectivity in the frontal cortex and a weak connectivity in the anterior-posterior pathway.The EC involving the PC/PCC significantly decreased in 1-4 Hz and 4-8Hz.In addition,the parameters of graph theory were significantly altered in several low-and high-frequency bands.Conclusion:CAE patients display frequency-specific abnormalities in the network pattern even during the inter-ictal periods,and the frontal cortex and PC/PCC may play crucial roles in the pathophysiology of CAE.The EC network of CAE patients is over-connective and more random during the inter-ictal periods,which is consistent with previous functional magnetic resonance imaging studies,and all suggest that the neural networks were disrupted during inter-ictal periods..