Fig. 5. Place field shifting resets and continues upon first re-exposure to N on day 2.
a Histogram of place field (PF) shifts across days for CA1 (left, n = 171 PFs) and CA3 (right, n = 43 PFs). The shifts were calculated as the difference between each PF’s center of mass (COM) on the last active lap on day 1 and first active lap in day 2. Only place cells with PFs on both days are included. Wilcoxon signed-rank test, two-sided. N.S., P > 0.05. b Comparison of COM position at the end of day 1 and COM position at the start of day 2 for PFs with day-to-day correlation >0.5 and significant shifting on day 1 (see Fig. 3c). Dashed diagonal: identity line. On day 2, PFs tend to reset towards the direction opposite of shifting on day 1. Two-sided Wilcoxon sign-rank test on Day 2-Day 1 difference from 0 for backward and forward shifting (P values and median in panel). c Comparison of PF shifting slope on both days. No clear correlation is observed, but the Day 2-Day 1 difference is not significantly different from 0 (Wilcoxon sign-rank, two-sided: P values and medians in panel) and individual PF shifting was slow (close to 0 cm/lap) on both days. d Population shift of PF COM. Left, mean ±SEM, over all PFs, of five-lap sliding average COM difference relative to lap 12 (see Methods), in N day 2. CA1 (green; n = 371 PFs from three mice) and CA3 (orange; n = 84 PFs from six mice). Linear regression, F test, ***P < 0.001 CA1, P < 1 × 10−100, CA3, P = 1.1 × 10−4. The resampling analysis (1000 random resamples matching the CA3 sample size) shows that CA1 slopes are always steeper than the CA3 slope, indicating that on day 2 the CA1 population shifts backward faster than CA3.