02102nas a2200229   4500008004100000245013500041210007100176260001200247490000700259520133100266653002101597653001601618653001701634653002701651653003501678653002501713653002501738100001701763700002101780700002301801856004801824       2011                        eng d00aSpace–time network connectivity and cortical activations preceding spike wave discharges in human absence epilepsy: a MEG study.0 aSpace–time network connectivity and cortical activations precedi  c05/20110 v493 aTo 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.10aAbsence epilepsy10aBeamforming10aConnectivity10aMagnetoencephalography10aNonlinear association analysis10aSmall world networks10aSpike wave discharge1 aGupta, Disha1 aOssenblok, Pauly1 aLuijtelaar, Gilles  uhttp://www.ncbi.nlm.nih.gov/pubmed/21533620