Mechanisms underlying epileptiform burst discharge

Studies of hyperexcitable cells in alumina-gel and penicillin epileptogenic foci suggest that epileptic neurons have intrinsic burst-generating properties. The burst mechanism may be released or triggered by a number of extrinsic factors which disrupt the normal depolarizing-hyperpolarizing balance. This paper presents the hypothesis that the most important influence for burst discharge is influx of calcium ions. This excitatory effect is modulated by synaptic inputs, hyperpolarizing conductances, cell morphology and membrane characteristics, and the extracellular milieu. The hypothesis incorporates fndings from both penicillin and alumin models of epilepsy and provides experimentally testable concepts for further investigation.