Figure 3.

A–C: Quantitative frequency analysis of “early” and “late” spontaneous seizures recorded in the same chronically epileptic, pilocarpine-treated rats. A1,2: Joint time frequency analysis spectrograms of “early” (2 days post-SE) and “late” (47 days post-SE) seizures in the same awake, epileptic animal, indicating when granule cell layer activities of different frequencies occurred in relation to the behavioral seizure onsets. Note that all high-frequency components (100 – 600 Hz) were greater in magnitude (darkness and height of peaks) in the early vs. late post-status epilepticus (SE) states, indicating a loss of epileptiform discharges over time. Also note that these high-frequency components occurred after, rather than before, the spontaneous behavioral seizure onsets (onset of forepaw clonus and rearing). B1: Averaged power spectrum of six randomly selected, 1-minute-long traces of granule cell activity during SE. B2,3: The six first and last spontaneous seizures during the “early” and “late” spontaneous seizures, respectively, in a typical epileptic pilocarpine- treated rat. Note that all frequencies between 100 and 600 Hz were higher during “early” seizures (B2) than during “late” seizures (B3), indicating the loss of high-frequency epileptiform granule cell discharges in the chronic epileptic state. C1: The average integral taken from the averaged power spectrum (100 – 600 Hz) in all five chronically epileptic rats that were implanted before SE. Note the significant loss (P< 0.012) of all high-frequency components. C2,C3: The average integrals taken from the averaged power spectra of the two high-frequency bands (165–175 Hz and 340–360 Hz) in all five epileptic rats. Note the significant loss (P < 0.012 and 0.014, respectively) of both narrow frequency bands. Calibration bars: 5 mV, 4 sec. From Harvey and Sloviter, 2005.