title: Phase-locking of epileptic spikes to ongoing delta oscillations in non-convulsive status epilepticus.
abstract: The EEG of patients in non-convulsive status epilepticus (NCSE) often displays delta oscillations or generalized spike-wave discharges. In some patients, these delta oscillations coexist with intermittent epileptic spikes. In this study we verify the prediction of a computational model of the thalamo-cortical system that these spikes are phase-locked to the delta oscillations. We subsequently describe the physiological mechanism underlying this observation as suggested by the model. It is suggested that the spikes reflect inhibitory stochastic fluctuations in the input to thalamo-cortical relay neurons and phase-locking is a consequence of differential excitability of relay neurons over the delta cycle. Further analysis shows that the observed phase-locking can be regarded as a stochastic precursor of generalized spike-wave discharges. This study thus provides an explanation of intermittent spikes during delta oscillations in NCSE and might be generalized to other encephathologies in which delta activity can be observed.
authors.affiliation: Department of Clinical Neurophysiology, MIRA-Institute for Biomedical Technology and Technical Medicine, University of Twente Enschede, Netherlands ; Computational Neuroscience Group, Department of Information and Communication Technologies, Center for Brain and Cognition, Universitat Pompeu Fabra Barcelona, Spain.
authors.forename: Rikkert
authors.initials: R
authors.lastname: Hindriks
authors.affiliation: Department of Electrical Engineering, Mathematics and Computer Science, MIRA-Institute for Biomedical Technology and Technical Medicine, University of Twente Enschede, Netherlands.
authors.forename: Hil G E
authors.initials: HG
authors.lastname: Meijer
authors.affiliation: Department of Electrical Engineering, Mathematics and Computer Science, MIRA-Institute for Biomedical Technology and Technical Medicine, University of Twente Enschede, Netherlands.
authors.forename: Stephan A
authors.initials: SA
authors.lastname: van Gils
authors.affiliation: Department of Clinical Neurophysiology, MIRA-Institute for Biomedical Technology and Technical Medicine, University of Twente Enschede, Netherlands ; Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente Enschede, Netherlands.
authors.forename: Michel J A M
authors.initials: MJ
authors.lastname: van Putten
keywords: absence seizure; absence status; delta oscillation; phase-locking; spike-wave discharge; thalamo-cortical system