Saturating LTD occludes BoNT/A actions, while reversing LTD with LTP restores BoNT/A efficacy.

<p><b>A</b>: Time course of the lack of effect of BoNT/A (200 ng/ml; solid bar) on fEPSP slopes (each point mean ± SEM of 8 slices) after saturation of LTD by four 2 Hz/5 min low frequency Schaffer collateral stimulus trains spaced 15 minutes apart. <b>B</b>: Time course of the depression of fEPSPs elicited by BoNT/A (200 ng/ml) after bath application of Cd²⁺ (5 µM) to reduce Pr by ∼50% in 8 slices. <b>C</b>: Time course in 8 slices of depression of fEPSPs by BoNT/A (200 ng/ml, bar) elicited after saturating LTD (4×2 Hz/5 min trains), then reversing it with induction of LTP by high-frequency theta-burst stimulation (TBS; 4x trains of 10 bursts of 5pulse/100 Hz each, 200 ms interburst interval).