CHARACTERISTIC INTERSPIKE INTERVALS OF PRIMARY UNIT AFTERDISCHARGES IN HIPPOCAMPAL NEURONS OF EPILEPTIC RAT
急性大鼠癫痫模型海马神经元原发性单位后放电脉冲间隔特征

Hippocampal primary unit afterdischarges induced by electric stimulation is one of the important pattern of activities related to rat epilepsy.The characteristics of its interspike intervals(ISI)and mean rate of the neuronal firing will be quantitatively analyzed.Acute tetanization(60 Hz,2 s,0.4~0.6 mA)of the right posterior dorsal hippocampus(ATPDH)or the right caudate putamen nucleus(ATRC)was used to induce electrogenic seizure-like activities.The results included:1)Hippocampal primary unit afterdischarges manifested two patterns of firing rate changes:from facilitation to inhibition and from inhibition to facilitation;their ISI value changed from small to large,which take the shape of dense spots called "head",and sparse spots called "tail",or reversely;2)Primary unit afterdischarges with "tail-head" distribution of ISI(35/57 trains)were mainly induced by the ATPDH;and the "head-tail" distribution of ISI(12/22 train)were mainly induced by the ATRC(P<0.05).3)An interactive "head-tail" or "tail-head" ISI distribution was observed between bilateral hippocampal neuronal firing after the ATRC;4)Hippocampal primary unit afterdischarges were closely related to seizure-like hippocampal EEG(70~150 Hz)or neocortical EEG(90~280 Hz)oscillations.It suggests that the hippocampal primary unit afterdischarges with "head-tail" or "tail-head" ISI distribution might reflect the level of tetani-evoked excitation or inhibition of neuronal firing,it might be helpful in analysis of the mechanism of epilepsy-related cellular activities in epileptic network.