Prolonged depolarizing potentials of the neurons in a strychninized isolated strip of the cat cerebral cortex

Reactions of isolated cortical slab neurons to the supracortical application of strychnine were investigated with intracellular registration in experiments on unanaesthetized and immobilized cats. It was shown that some neurons demonstrated prolonged depolarizing potentials (PDP) spontaneously and as reactions to single intracortical electrical stimuli. The development of these potentials could be a result of transformation of the reaction of the "paroxysmal depolarizing shift (PDS)--hyperpolarization" type, where hyperpolarizations were replaced by depolarizing potentials. A gradual increase of depolarizing afterpotentials resulted in DDP generation. These transformations, as a rule, were accompanied by amplification of the summary epileptiform activity in an isolated cortical slab. The suggestion was made that the DDP generation was determined by an increase in the Ca(++)-conductance of the neuronal membrane in an isolated cortical slab with the intensification of paroxysmal reactions.