| Abstract: | After strong tetanization epileptiform after-discharges occur in the neurones of the sensorimotor cortex of unanaesthetized rabbits, they take the form of bursts of impulses occurring at intervals of 150–600 msec. The bursts are caused by paroxysmal depolarization shifts (PDS) of the membrane potential (MP). When the MP is reduced to 10–20 mV, on account of the considerable damage to the neurone the PDS give way to hyperpolarization oscillations. Unlike the prolonged action potentials (AP), which are quite frequently recorded in damaged cells, the intracellular PDS and the extracellular bursts of after-discharges show no change in frequency when a current is passed through the recording microelectrode. It was found impossible to suppress the generation of PDS by means of a hyperpolarizing current (1–3·10–9 A), or to evoke PDS by a depolarizing current. Therefore we were unable to confirm the hypothesis that PDS occur as a result of reorganization of the generation of the electrical impulse. Support is given to the hypothesis that the PDS are altered and enormously potentiated excitatory postsynaptic potentials (EPSP)Brain Institute, Academy of Medical Sciences of the USSR, Moscow, Translated from Neirofiziologiya, Vol. 2, No. 5, pp. 460–468, September–October, 1970. |
