Extended Data Fig. 3: Theta phase locking changes are not caused by decreased power or specific to reference location.

a. Example clustering of single units from a single channel set in one animal using principal components, peak amplitude, and trough amplitude. b. Units were characterized as putative interneurons based on complex spike index (CSI), mean autocorrelogram (Mean AC), and mean firing rate. N = 5 Control, N = 5 Epileptic animals. c. Example phase locking in a CA1 interneuron. Top, mean waveforms from each recorded channel within the pyramidal layer. Middle, spike raster of 300 theta cycles during running, with the proportion of spikes occurring during each phase of theta. Bottom, Rose plot of firing phase relative to theta. This cell has a modulation index (r-value) of 0.41 and preferred firing phase (mu) of 189°. d–g. Theta cycles were subsampled to match power between control and epileptic mice. This did not change the results as CA1 interneurons in epileptic mice were less phase locked than in control mice (d; n = 71 Control cells, n = 34 Epileptic cells, Unpaired t-test, P < 0.001), while their preferred phase was not different (e; Kuiper circular test, P > 0.05). There were no differences in the modulation of DG interneurons (f; n = 34 Control cells, n = 22 Epileptic cells, Unpaired t-test, P = 0.80) but there were differences in the preferred phase of DG interneurons (g; Kuiper circular test, P < 0.001). h, i. Phase locking of DG interneurons to theta in the lacunosum moleculare. No difference was found in modulation (h; n = 34 Control cells, n = 41 Epileptic cells, Unpaired t-test, P = 0.25) but the distributions of preferred phases differed between the groups (i; Kuiper circular test, P < 0.001). j-k. Phase locking of DG interneurons to the theta in hilus of DG. No difference was found in modulation (j; n = 34 Control cells, n = 41 Epileptic cells, Unpaired t-test, P = 0.64) but the distributions of preferred phases differed between the groups (k; Kuiper circular test, P < 0.001). N = 5 animals per group for all panels. Error bars represent 1 S.E.M. ***P < 0.001.