PARTIAL HIPPOCAMPAL KINDLING INCREASES PAIRED-PULSE FACILITATION AND BURST FREQUENCY IN HIPPOCAMPAL CA1 NEURONS

For up to 3 weeks after 15 evoked afterdischarges (partial kindling) in the hippocampus in vivo, paired-pulse facilitation of the CA1 apical dendritic excitatory postsynaptic potentials (EPSPs), recorded from single neurons in vitro, was significantly larger in neurons of kindled than control rats. Partial kindling did not significantly affect the resting membrane potential, the threshold or size of the action potential (AP), the fast afterhyperpolarization, input resistance, time constant or the EPSP threshold. The number of APs induced within the initial 20 ms of a long-duration 0.5-nA depolarizing current was significantly higher in the kindled than control neurons. The increase in paired-pulse facilitation and intrinsic spiking in hippocampal CA1 after partial kindling may contribute to an increase in seizure susceptibility.