Sleep oscillations in corticothalamic neuronal networks and their development into self-sustained paroxysmal activity

Electrophysiological studies in cats have shown that one of the most common forms of sleep oscillation, spindling, may develop into spike-and-wave discharges through repetitive spike-bursts transmitted along thalamocortical or corticothalamic axons. The lowered frequency (from around 10 Hz to 3 Hz) can be explained by the abnormally increased duration of an IPSP mediated by GABA receptors. The administration of ethosuximide has a twofold effect resulting in a diminished spindling activity of the reticular thalamic nucleus as well as a decrease in the incidence of epileptic spike-and-wave discharges. Self-sustained paroxysmal activity may develop during EEG synchronized states by repetitively setting into action reciprocally connected structures.