Pathophysiology of absence epilepsy: Insights from genetic models.

Absence Epilepsy (AE) is a prototypic epileptic syndrome that develops during brain maturation but cannot be fully explored in human patients. Genetic animal models, especially rats with spike-and-wave discharges recorded on the electroencephalogram, the hallmark of absence seizures, offer strong face validity with the human pathology that allows precise exploration of the pathophysiology of this form of epilepsy. Using an array of different methods, recent studies have demonstrated that spike-and-wave discharges are initiated in the primary somatosensory cortex and then rapidly propagate to motor cortices and thalamic nuclei. More specifically, in vivo electrophysiological intracellular recordings showed that the pyramidal neurons of the deep layers of this cortex exhibit fast activation, hyperexcitability and hypersynchronizing characteristics in favor of their role as ictogenic neurons in absence seizures. Furthermore, longitudinal studies during brain maturation suggest the progressive development of these features. Exploration of the different key players in the maturation of the primary somatosensory cortex should determine the anomalies that lead to the development of the cortical generator of absence seizures.