Multiple but not single anisomycin injections after context reexposure impair performance. (a) Freezing is shown during a 3-min retrieval session, which was followed either immediately (Ani Single) or immediately, 2, 4, and 6 h later (Ani Multiple) by 50 mg/kg anisomycin or saline (Sal). A 3-min test session occurred the following day. (b and c) During the retrieval session, different groups of mice were exposed to the conditioning context, followed immediately, 2, 4, and 6 h later by injections of 50 mg/kg anisomycin (Ani Ret) or saline (Sal Ret). Other mice did not receive the retrieval trial but received the same injections of anisomycin (Ani No Ret) or saline (Sal No Ret). Freezing is shown during retrieval and during a 3-min test session (b) and a 12-min test session (c) the day after retrieval. Error bars indicate SEM.