Fig. 4: Modulation of receptive fields, regional differences and neuronal replay.

a, Top, selective hippocampal–entorhinal neurons that preferred a stimulus at an outer node (n = 119) responded significantly differently to stimuli from indirect-inner versus indirect-outer nodes, suggesting that these neurons’ receptive fields progressively elongated. Bottom, there was no such effect for neurons that preferred a stimulus at an inner node (n = 144), which suggests that their receptive fields were rather symmetrical. Plots show the mean Euclidean distance (±s.e.m.) between responses to respective stimuli (data centred on PRE and z-scored per neuron). P values from Wilcoxon rank-sum tests (two-sided, FDR-corrected). Orange circles indicate the locations of preferred stimuli. Orange areas illustrate the hypothesized shapes of receptive fields. b, The successor representation in the hippocampus was more impaired by growing proportions of artificially removed neurons than in the entorhinal cortex. Similarity to the successor template is plotted as a function of the percentage of removed neurons (relative to 1% of neurons removed; for each 1% step, we randomly selected a given proportion of neurons 10,000 times). The actual difference between the third quartiles was compared with the same difference in 1,000 permutations of the region labels. c, The replay analysis focused on three-element graph trajectories consisting of one seed node, a direct node and an indirect node. We analysed triplets of selective hippocampal–entorhinal neurons (recorded in the same session) whose preferred stimuli mapped onto those trajectories. Only spiking activity during breaks between phases was analysed (B1–B7). d, Examples of pyramid-congruent replays detected for triplets of selective hippocampal–entorhinal neurons. Coloured circles indicate the graph location of each neuron’s preferred stimulus during PRE. Raster plots show the spiking activity of ‘direct’ and ‘indirect’ neurons during each spontaneous repetition of a given replay. The bottom plot shows combined spiking activity across all repetitions and the mean spikes’ latencies (±s.e.m.). Plots are time-locked to the seed neuron’s relevant spikes. The probability of pyramid-congruent replays increased throughout the study and in B2–B7 was significantly higher than that of incongruent replays (1,000 random permutations of ‘direct’ and ‘indirect’ spike labels). P values in b,d were calculated as the number of permutations with a higher difference than the one actually detected, divided by the total number of permutations. If in none of the permutations the difference was above the actual one, the P < 0.001 range is reported. No adjustment for multiple comparisons was applied in d.