Fig. 3.

The frequency, but not the amplitude, of the miniature IPSCs (mIPSCs) is increased in rats that experienced seizures. a, mIPSCs from CA1 pyramidal cells from a control rat and from a rat that experienced hyperthermia-induced seizures 1 week before recording (HT). The frequency of the miniature IPSCs in CA1 pyramidal cells was considerably increased in HT rats. b and c, Summary data of the mIPSC inter-event interval (b) and amplitude (c) from cells similar to those in a as well as from cells from hyperthermic control rats (n = 14 cells in all three groups). The near-doubling of the frequency of the mIPSCs in the HT group, corresponding to a large decrease in the inter-event interval in b: median inter-event interval in normothermic control, 113.1 ms (solid lines); in HT, 64.6 ms (dashed lines); in hyperthermic control, 119.9 ms (dotted lines), without any change in the amplitude (or kinetics), indicates that the potentiation of the IPSCs has a presynaptic locus. Insets, 1 week after kainic acid-induced seizures at postnatal day 10, no equivalent alterations in the frequency of the mIPSCs could be seen (in addition, in contrast to the unchanged mIPSC amplitude after hyperthermia-induced seizures, there was a small, but statistically significant increase in the amplitude of the mIPSCs after kainate injection, compared with that of littermate controls); n = 12 cells in both the control (solid lines) and kainate-injected (dotted lines) groups.