| Abstract: | Intracellular response in neurons and glial cells of an isolated cortical slab to direct electrical stimulation of the slab following surface application of strychnine was investigated during experiments on immobilized unanesthetized cats. Strychnine induced single epileptiform discharges and after-discharges in the slab and in the neurons it contained in the form of large-scale paroxysmal depolarization shifts (PDS) in membrane potential (MP). Spontaneous summated epileptiform discharges and neuronal activity in the units examined were not very synchronized. Electrical stimulation induced generalized paroxysmal activity in the isolated slab. Neuronal PDS were accompanied by refractory periods, onset of which did not depend on MP level. Strychnine increased the number of neurons manifesting background activity in which action potentials were generated by rhythmic depolarizing MP waves of extrasynaptic origin. Epileptiform response in strychninized cortical isolated slabs to presentation of single stimuli is accompanied by major depolarization shifts in the MP of glial cells. Paroxysmal excitation is thought to be triggered in strychninized isolated cortical slabs by extrasynaptic factors and closely linked to altered concentration of extracellular potassium.I. I. Mechnikov University, Odessa. Translated from Neirofiziologiya, Vol. 22, No. 1, pp. 23–29, January–February, 1990. |
