TY - JOUR T1 - Space–time network connectivity and cortical activations preceding spike wave discharges in human absence epilepsy: a MEG study. JF - Medical and Biological Engineering and Computing Y1 - 2011 A1 - Disha Gupta A1 - Pauly Ossenblok A1 - Gilles van Luijtelaar KW - Absence epilepsy KW - Beamforming KW - Connectivity KW - Magnetoencephalography KW - Nonlinear association analysis KW - Small world networks KW - Spike wave discharge AB - To describe the spatial and temporal profiles of connectivity networks and sources preceding generalized spike-and-wave discharges (SWDs) in human absence epilepsy. Nonlinear associations of MEG signals and cluster indices obtained within the framework of graph theory were determined, while source localization in the frequency domain was performed in the low frequency bands with dynamic imaging of coherent sources. The results were projected on a three-dimensional surface rendering of the brain using a semi-realistic head model and MRI images obtained for each of the five patients studied. An increase in clustering and a decrease in path length preceding SWD onset and a rhythmic pattern of increasing and decreasing connectivity were seen during SWDs. Beamforming showed a consistent appearance of a low frequency frontal cortical source prior to the first generalized spikes. This source was preceded by a low frequency occipital source. The changes in the connectivity networks with the onset of SWDs suggest a pathologically predisposed state towards synchronous seizure networks with increasing connectivity from interictal to preictal and ictal state, while the occipital and frontal low frequency early preictal sources demonstrate that SWDs are not suddenly arising but gradually build up in a dynamic network. VL - 49 UR - http://www.ncbi.nlm.nih.gov/pubmed/21533620 IS - 5 ER -