Fig. 8. Interneuron firing predicts the spike latency of pyramidal cells during optogenetically induced SWRs.

a Top: CA1 local field potential (LFP) around an example of optogenetically induced SWR-like high-frequency oscillations. Bottom: Light onset-triggered average of LFP wavelet spectrogram of 500 optogenetically induced SWRs in an example recording session. b Average peristimulus time histogram of all interneurons (n =  19) that both displayed pre-SWR firing and were associated with significantly delayed spike timing of at least one pyramidal neuron (defined in Fig. 7). The values are Z-scored based on the 150-ms baseline period prior to the light onset followed by subtraction of the mean value. c The spike latencies of pyramidal neurons, averaged across light pulses, as a function of the within-pulse firing rates of the corresponding interneurons. Only interneuron-pyramidal pairs in which an effect of pre-SWR inhibition on pyramidal spike timing was observed were considered. The black line represents the least-squares regression line. Spearman ρ = 0.365, P = 0.024, a t-test of the correlation coefficients (two-sided), n = 38 pairs. d Average light pulse-associated spike latencies of the interneuron and pyramidal cell in each pair. Black, diagonal showing equal spike latencies. In 32/38 pairs (84.2%), the interneuron spike latencies were shorter than those of the associated pyramidal cells.