Fig. 1: Neural dynamics of CA1-projecting CA3 neurons during spatial learning.

A The schematic drawing shows the experimental setup for recording the neural activities during the Morris water maze (MWM) task. B AAV (250 nl AAV/Retrograde-syn-jGCaMP7s; 5.0E + 12 vg/ml) is injected into the CA1 the dorsal hippocampus (DHP). AAV injection (mm): AP = −1.80, ML = 1.30, DV = 1.25; Fiber implantation (mm); AP = −1.80, ML = 2.35, DV = 1.80. C Fluorescent image after adjusting the look-up table (LUT) showing the AAV expression in DHP and fiber track in CA3. Scale bar: 1000 µm. D Magnified image from Fig. 3C (dashed rectangle) shows optical fiber monitors the neuronal activities of CA3-SC afferents. Scale bar: 500 µm. E Double Y curves depict the escape latency and Ca²⁺ responses of GCaMP 7s-expressing mice during spatial learning. F The Ca²⁺ responses in trial-1 (upper) and trial-10 (lower) in GCaMP 7s-expressing mice. G The averaged Ca²⁺ responses in trial-1 (blue line) and trial-10 (red line). H Data were normally distributed (Shapiro–Wilk: Trial 1, p = 0.538; Trial 10, p = 0.288) with equal variances (Levene’s test, p = 0.934). Statistical comparison of the averaged 5 s (after the 0 s) of Ca²⁺ responses in trial 1 (blue dots) and trial 10 (red dots) after mice are released into the swimming pool. I The Ca²⁺ responses in trial 1 (upper) and trial 10 (lower) in GFP-expressing mice. J The averaged Ca²⁺ responses in trial 1 (blue line) and trial 10 (red line) in control mice. K Data met normality (Shapiro–Wilk: Group A, p = 0.879; Group B, p = 0.562) and variance homogeneity (Levene’s p = 0.714) assumptions. Statistical comparison of the averaged 5 s of Ca²⁺ responses in trial 1 (blue dots) and trial 10 (red dots) after control mice are released into the swimming pool. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001; ns not significant. Data are reported as mean ± SEM.