Extended Data Fig. 3: Additional analyses on abDGC temporal dynamics.

(a-c) Spike coupling of abDGCs versus other DG PCs to slow gamma oscillations. (a) Top: Raw wide-band LFPs (black trace) recorded from the dentate granule layer showing an example single theta cycle (with red trace = theta filtered signal) nesting slow gamma (30-55 Hz) oscillations (with blue trace = corresponding slow gamma filtered signal from the black trace). (b) Mean spike probability of abDGCs (purple) versus other DG PCs (blue) as a function of ongoing slow gamma phase (dashed line, with two cycles for clarity). Both abDGCs and other DG PCs are locked to the peak of local slow gamma, but the strength of modulation was greater in abDGCs. Data taken from ‘laser-off’ periods. Spike probabilities were normalized to the cell’s baseline spike rate. (c) Corresponding estimation plot used to visualize the effect size for differences in the strength of modulation (mean resultant length, MRL) of abDGCs versus other DG PCs. The strength of slow gamma modulation was significantly greater for abDGCs compared to other DG PCs (p = 0.005, two-sided permutation test). (d) Spike discharge probability of DG, CA3 and CA1 PCs (top row) and interneurons (bottom row) w.r.t. spontaneous spike discharge of high-firing-rate DG PCs. High firing rate DG PCs were selected to best match the firing rates of concomitantly recorded abDGCs from each day. For each population: the left panel reports spiking probability referenced to spontaneous high-rate DC PC spikes (black histogram; with red line: the corresponding shuffled spike distribution with the original theta phase of each spike preserved); the right panel shows the observed minus the shuffled distribution. The dotted blue lines show the standard error of the mean. (Principal cells: abDGC n = 89, CA3 n = 84, CA1 n = 584; Interneurons: DG n = 232, CA3 n = 15, CA1 n = 104 cell-pairs in 8 mice). (e) Estimation plot showing the mean firing rate of the 33 abDGCs and their 33 rate-matched DG PCs in novel versus familiar environment. Only the abDGCs showed a significant increase in firing rate in the novel environment (p = 0.001, two-sided paired permutation test). Panels c,e show Cumming estimation plots as described in Extended Data Fig. 1e. ***p < 0.001, **p < 0.01.