Fig. 4: With reduced DG input, peak probability of CA3 spiking shifts to earlier theta phases. | Nature Communications

Fig. 4: With reduced DG input, peak probability of CA3 spiking shifts to earlier theta phases.

From: Distinct roles of dentate gyrus and medial entorhinal cortex inputs for phase precession and temporal correlations in the hippocampal CA3 area

Fig. 4

a Left, For control CA3 cells, distribution of spike incidence across early, middle, and late theta phases. Top right, The proportion of CA3 spikes early in the theta cycle was markedly increased with DG lesions (mean theta phase: CTRL(DG) n = 84 cells, mean phase = 173.4°, LESION(DG) n = 68 cells, mean phase = 74.1°, χ2 statistic = 18.4, p = 0.0001, χ2 test for proportion of spikes in each of the three thirds). Dotted lines, data from control CA3 cells, as shown to the left. Bottom right, with MEC lesions (LESION(MEC)), there was no change in the phase distribution of CA3 spikes (CTRL(MEC) n = 101 cells, mean phase = 157.1°, LESION(MEC) n = 158 cells, mean phase = 172.3°, χ2 statistic = 0.74, p = 0.69; χ2 test for proportion). b Average number of spikes over a 360°-cycle from the first spike in the train. In trains from cells of DG-lesion rats, the median number of initial-cycle spikes increased by 23.8% compared to control cells (from 2.61 to 3.23, n = 84 CTRL(DG) and 68 LESION(DG) cells, z-statistic = – 4.38, p = 1.2 × 10–5, MW test). In MEC-lesion rats, the median number of initial-cycle spikes increased by 16.5% compared to control trains (from 2.49 to 2.9 spikes, n = 101 CTRL(MEC) and 158 LESION(MEC) cells, z-statistic = – 2.74, p = 0.006, MW test). c Fraction of CA3 spikes at early, middle, and late phases of the theta cycle as a function of normalized (%) distance during the train. At the onset of control trains, a low proportion of spikes is typically observed at early phases, but this proportion increases with DG lesions. d Top, DG lesions selectively increased the variability of spike phase in the first half of a spike train (from 5% to 45% of the normalized distance, MW tests; Holm-Bonferroni corrected; see Supplementary Table S2 for statistics). See Fig. 1b, for example spike trains that show this effect. Bottom, MEC lesions did not increase the variability of theta phase along the distance through the field (MW tests; Holm-Bonferroni corrected; Supplementary Table S2). * p < 0.05, ** p < 0.01, *** p < 0.001. For most theta cycle-based analyses, similar results were obtained when repeating the analyses by using the cells’ place fields rather than the cells’ spike trains (Supplementary Fig. S7ii). Source data are provided as a Source Data file.

Back to article page