[The cellular reactions of a strychninized isolated strip of the cat cerebral cortex]

Reactions of neuronal and glial cells of an isolated cortical slab to direct electrical stimulation after supracortical strychnine application were investigated in experiments on immobilized and unanaesthetized cats. Strychnine evoked single epileptiform discharges and afterdischarges in the isolated cortical slab and large paroxysmal depolarization shifts (PDS) of the membrane potential (MP) in the neurons. It was shown that spontaneous summary epileptiform discharges and cellular activity of neurons investigated were synchronized slightly. Electrical stimuli produced a generalized paroxysmal activity in the isolated slab. Neuronal PDSs were accompanied by refractory periods which development did not depend on the MP level. Strychnine enhanced a number of neurons with the background activity in which PDS were generated by rhythmic depolarizing MP oscillations of the nonsynaptic origin. It was shown also that epileptiform reactions of the strychninized isolated cortical slab to the single stimuli were accompanied by large depolarization shifts of the glial cells' MP. The suggestion is made that the paroxysmal excitation development in the strychninized isolated cortical slab was determined by non-synaptic factors and was strongly related to the changes of the extracellular potassium concentration.