Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

PURPOSE: To analyze the cellular and network mechanisms of sustained seizures, we reviewed the literature and present new data on in vitro epileptiform events. We considered single and recurring synchronized population bursts occurring on a time scale from tens of milliseconds to 1 min. METHODS: We used intracellular and field potential recordings, together with computer network simulations, derived from three types of experimental epileptogenesis: gamma-aminobutyric-acidA (GABAA) blockade, low extracellular [Mg2+]o, and 4-aminopyridine (4-AP). RESULTS: In all three models, sustained depolarizing synaptic currents developed, either through N-methyl-D-aspartate (NMDA) receptors, depolarizing GABAA receptors, or both. Ectopic action potentials (APs), probably originating in axonal structures, occurred in 4-AP and (as shown by other researchers) after tetanic stimulation; ectopic APs, occurring at sufficient frequency, should also depolarize dendrites, by synaptic excitation, enough to trigger bursts. CONCLUSIONS: Ictal-like events appear to arise from two basic mechanisms. The first mechanism consists of sustained dendritic depolarization driving a series of dendritic bursts. The second mechanism consists of an increase in axonal and presynaptic terminal excitability driving a series of bursts analogous to interictal spikes.

Type

Journal article

Journal

Epilepsia

Publication Date

09/1996

Volume

37

Pages

879 - 891

Keywords

4-Aminopyridine, Action Potentials, Animals, Axons, Bicuculline, Brain, Computer Simulation, Dendrites, Electroencephalography, Epilepsy, Hippocampus, Humans, In Vitro Techniques, Male, Microelectrodes, Models, Neurological, Neural Networks (Computer), Neurons, Pyramidal Cells, Rats, Rats, Sprague-Dawley, Receptors, GABA-A, Receptors, N-Methyl-D-Aspartate, Synaptic Transmission