Figure 3.

Pairing-induced changes in synaptic strength, potency, and failure rate. A–C, Histograms showing the distribution of normalized (Δ_N = X_post− X_pre/X_post + X_pre) changes in average uEPSC peak amplitude including (A, strength) and excluding (B, potency) failures and failure rate (C). Connections that showed LTP (as defined by an increase in normalized strength change, +Δ_N strength, p < 0.05, Wilcoxon's test) are shown in red, those that showed LTD (−Δ_N strength, p < 0.05, Wilcoxon's test) in blue, and connections whose strength did not change after pairing (p ≥ 0.05, Wilcoxon's test) as gray. D, Changes in strength (black bars), potency (gray bars), and failure rate (white bars) for all studied L4–L4 cell pairs (n = 42). Each group of three bars corresponds to a pair recording experiment sorted by group from lowest Δ_N to the left to highest Δ_N to the right. Underlined areas indicate pairs that underwent significant depression (blue, n = 19), potentiation (red, n = 7), or no change (gray, n = 16). E, F, Correlations between Δ_N strength and Δ_N potency (A; R² = 0.57, p < 0.001) and Δ_N failure rate (B; R² = 0.42, p < 0.001). G, Correlation between Δ_N potency and Δ_N failure rate (R² = 0.34, p < 0.001).