Fig. 1

Four-AP treatment induces epileptiform activity in urethane-anaesthetized rats. Representative EEG traces are shown that were recorded between a frontal and an occipital electrode A just before and B 2.5–3.0 h after 4-AP treatment. The 4-AP-induced activity increase in the higher frequency bands and the abolishment of the urethane-induced slow waves can be seen on the raw traces. C, D The EEG power spectra and spectrograms (inset figures) show that this 4-AP-induced activity increase was the most remarkable around 60 Hz (i.e., in the gamma frequency range). The spectrograms were calculated from 300 s long recordings and the color scale shows EEG power on a dB scale from 25 to 50 dB. E, F The area under the power spectra was calculated by integration for ranges 0–5 Hz and 50–80 Hz (noted by lines and shaded areas on plot C and D) and area data were statistically compared using paired sample t-test. Data are shown as mean ± SD (n = 11; ***P < 0.001)