Recording and analysis profiles of neuronal ensembles.

<p><b>A</b>. Histological locations (asterisks) of recording electrode tips in the hippocampus. Scale bar indicates 500 μm. <b>B</b>. Waveforms of hippocampal spikes (yellow) and noise signals (whitish-gray) separated by morphology (calibration: 0.2 ms, 100 μV). <b>C</b>. Clusters of single units and noise signals separated according to the first two principal components (PC1 on x-axis; PC2 on y-axis). <b>D</b>. Autocorrelogram of a single unit with an absolute refractory period of a minimum of 2 ms.</p

Cross-correlation histograms show coincident firing of a sample pair of neurons from one SE rat between the baseline period and early preictal period.

<p>Black line indicates the raw correlation smoothed with a 7 ms boxcar window (CCH_raw). The jitter-predicted correlation (Jitter₅₀, blue) indicates the correlation driven by common input, as determined by jitter shuffling of the spike train with a 50 ms window. The cross-correlogram (‘CCG’, or COIN₅₀, red) corresponds to pair-specific coincident activity, defined as the difference between raw coincidences and jitter coincidences.</p

Changes in the firing rates of hippocampal units in pilocarpine-treated rats.

<p><b>A</b>. Relative discharge rates 30 min before and after pilocarpine treatment in SE (red) and nonSE (blue) rats. <b>B</b>. Rate-by-rate comparison of firing rate change before [-10∶0 minute] and after [5∶15 minute] pilocarpine injection (see gray zones in panel A) of individual neurons from SE (red dots) and nonSE (blue dots) rats. Filled circles indicate significant difference of firing rate after pilocarpine injection. Open circles indicate no change in firing rate.</p

Outline of the experimental procedure.

<p><b>A</b>. Experimental steps for induction of status epilepticus (SE). <b>B</b>. Temporal profiles of SE in 9 rats after injection of pilocarpine. No SE was identified in 12 rats. The black bar indicates the occurrence of SE. The early post-pilocarpine period was defined as the time period of 5–15 min after injection of pilocarpine, as delimited between the two vertical dashed lines.</p

Changes in functional connectivity across all neuronal pairs from cross-correlation analysis.

<p>Upper panel shows the raw correlation (CCH_raw), correlation driven by common input (Jitter₅₀), and correlation of neuronal pairs (COIN₅₀) based on peak values at baseline and early preictal periods. Lower panel shows log ratios of the coincident peak of early preictal period to that of baseline period. The vertical scatter plots integrate the distributions of all ratio results in CCH_raw, Jitter₅₀, and COIN₅₀. Each data point represents a result from one neuronal pair. The mean peak ratio is indicated by black horizontal line, and the median peak ratio is shown in green. The correlation value of neuronal pairs was significantly larger in nonSE rats than SE rats.</p

Local field potentials in 10-sec time windows of representative SE and nonSE rats at baseline period (upper panel) and at 5 min (middle panel) and 85 min (lower panel) after pilocarpine treatment.

<p>Local field potentials in 10-sec time windows of representative SE and nonSE rats at baseline period (upper panel) and at 5 min (middle panel) and 85 min (lower panel) after pilocarpine treatment.</p

Mean onset time (± SEM) of status epilepticus (SE) relative to behavioral and local field potential (LFP) patterns after i.p. pilocarpine injection in nonSE and SE groups.

<p>Mean onset time (± SEM) of status epilepticus (SE) relative to behavioral and local field potential (LFP) patterns after i.p. pilocarpine injection in nonSE and SE groups.</p