Figure 1.

Induction of the prototypic afterdischarge under a glutamate-blocking condition in hippocampal pyramidal cells. A, Local field potentials (FP) showing HFS-induced seizure-like afterdischarge in normal ACSF (left) and prototypic afterdischarge in the presence of the ionotropic glutamate receptor antagonists CNQX (10 μm) and AP5 (50 μm; right). Whereas the seizure-like afterdischarge was observed at both local (<200 μm from the site of stimulation) and distant (>500 μm) recording sites, the prototypic afterdischarge (arrowhead) was detected only at the local recording site in the same hippocampal CA1 slice. B, Oscillatory depolarizing responses during the seizure-like afterdischarge (left) and the prototypic afterdischarge (right) in a pyramidal cell recorded in the gramicidin-perforated patch-clamp method (PC_gpp). Note that these responses were synchronous with the population spikes in the field potential (top, arrowheads) and that the generation of spikes indicates not only depolarizing but also excitatory responses in the pyramidal cell. Insets, Synaptic responses evoked by a single shock of electrical stimulation (stim). Calibration: 25 ms, 0.2 and 2.5 mV. C, Summary of the seizure-like afterdischarge (left) and the prototypic afterdischarge (right) in the pyramidal cells. Top, Time course of the seizure-like and prototypic afterdischarges in the pyramidal cells (boxes and bars indicate the mean and SD of start and end time, respectively). Middle, Membrane potential changes after the electrical induction (spikes were clipped in advance; black and gray lines indicate mean and SD, respectively). Bottom, Spiking rate changes after the electrical induction (circles and bars indicate mean and SD, respectively).