[The postsynaptic components of the paroxysmal reactions of the neurons in the strychninized neocortex]

Intracellular responses of neurons of cortical strychninized suprasylvian gyrus were investigated in experiments on immobilized and unanaesthetized cats. Paroxysmal depolarizing shifts (PDS) of the neuronal membrane potential were registered. They consisted of the burst discharge (BD) and slow depolarization wave. By means of intracellular stimulation it was shown that PDS could be summarized and were able to change their form and size. BD in PDS were triggered by large EPSPs which could be elicited from paroxysmal responses. Presumably, the intradendritic recordings have shown the presence of large EPSPs during generation of epileptiform discharges in the neocortex. In some neurons PDSs were accompanied by hyperpolarizing potentials which were apparently IPSPs because they were reversed at the intracellular Cl- injections. The contribution of excitatory and inhibitory synaptic influences to the neuronal paroxysmal responses is discussed.