Fig. 4: Co-activation of CA3-CA1 and MEC-CA1 pathways induces heterosynaptic LTP.
From: The perforant pathway and CA3-Schaffer collateral afferents coordinate to regulate spatial learning
AThe schematic drawing shows the AAVs injection (AAV9-CaMKIIα-ChrimsonR-mCherry in CA3, AAV9-CaMKIIα-Chronos-GFP/AAV9-CaMKIIα-GFP in MEC) for targeting the CA3-SC afferents and PP inputs in WT mice. The injection volumes of AAVs are the same as Fig. 3. B Upper: AAV expression (ChrimsonR-mCherry) in CA3 neurons and SC fibers, and AAV expression (Chronos-GFP) in MEC-CA1 terminals in DHP. Scale bar: 1000 μm; Bottom: AAV expression (Chronos-GFP) in MEC neurons. Scale bar: 1000 μm. AAV injection (mm) in CA1: AP = −1.80, ML = 1.30, DV = 1.25; In MEC: AP = −5.10, ML = 2.30, DV = −3.25/−2.75. C Cartoon illustrates the 473 and 635 nm light stimulation of ChrimsonR-expressing CA3-SC afferents and Chronos-expressing PP inputs in the DHP, respectively. And recording of 473 and 635 nm L-fEPSPs in DHP. D The protocol of dual-colol theta burst light stimulation (DL-TBS) for activating the CA3-SC afferents and PP inputs. E DL -TBS successfully induced a robust and persistent hetero-LTP in CA3-SC afferents compared to the control group (only GFP-expressing PP inputs). F Data met normality assumptions (Shapiro–Wilk p > 0.05) but violated variance homogeneity (Levene’s p < 0.001). Statistic comparison of 635 nm L-fEPSPs before and after DL-TBS. N = 4 mice, n = 8 recordings in DL-TBS group; N = 4 mice, n = 7 recordings in control. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001; ns not significant. Data are reported as mean ± SEM.
