Figure 8. Temporal constraints to the induction of heterosynaptic LTD.

A, the effect of conjunctive pairing of PF₁ responses with depolarisation at 1 Hz for 1 min (arrow). Large-amplitude baseline PF responses were used (n = 6). B, using large-amplitude baseline PF responses, PF₁ stimulation was paired with depolarisation at 1 Hz for 5 min (horizontal filled bar). PF₂ was not activated during pairing and stimulation was not resumed for a further 20 min (n = 6). C, bar chart comparing PF₁ (▪) and PF₂ (□) responses measured 30 min after (from left to right): 1 min conjunctive pairing of PF₁ with depolarisation, 5 min conjunctive pairing with immediate resumption of both PF₁ and PF₂ stimulation, and 5 min conjunctive pairing with delayed PF₂ stimulation. Measurements after 50 min for the last two of these three experiments are shown on the right. Asterisks indicate a significant difference between PF₁ and PF₂ responses (P < 0.05, Wilcoxon signed-rank test, 2-tailed).