Models of primary generalized epilepsy.

The most important recent development in primary generalized epilepsy has been the use of in-vitro and in-vivo models to delineate the neuronal populations and intrinsic mechanisms, which generate the synchronized thalamocortical burst-firing of absence seizures. Candidate molecular mechanisms, which may be critically involved in the pathogenesis of absence seizures in selected animal models, include the following: altered biophysical properties of T-type calcium channels in the genetic absence epilepsy rat of Strasbourg (GAERS) model; increased numbers of gamma-aminobutyric acid, B subtype receptors in the lethargic mouse (lh/lh mouse) model; and changes in the subunit composition of gamma-aminobutyric acid, A subtype receptors in the GAERS model. Regarding generalized convulsive seizures, neuronal populations within the inferior and superior colliculi appear to regulate seizures in the genetic epilepsy-prone rat (GEPR) model, and subpopulations within the substantia nigra pars reticulata (SNR) appear to regulate seizures in the fluorothyl model. Deficiencies in the function of GABAergic and noradrenergic receptors may underlie generalized convulsive seizures in the GEPR model.