Retrieval of one of the components of the compound stimulus triggers in the LA protein synthesis-dependent memory reconsolidation of the other component. (A) Rats trained using a compound stimulus (light + tone) conditioning procedure and infused with anisomycin in the LA after exposure to the light component of the compound show decreased freezing to the tone during long-term memory (LTM) test. Top panel: chart showing the experimental design. Left graph: mean ± SEM freezing in seconds of rats treated with ACSF or anisomycin in response to the light exposure during reactivation. Right graph: mean ± SEM freezing in response to the tone averaged across three tone presentations during LTM. (B) Rats trained with a compound stimulus and infused with anisomycin in the LA with no reactivation of memory do not show any loss of freezing during LTM. Top panel: chart showing the experimental design. Left graph: contextual freezing in seconds (mean ± SEM) of rats treated with ACSF or anisomycin during context exposure. Right graph: mean ± SEM freezing in response to the tone averaged across three presentations during LTM. (C) When the same stimuli (light and tone) are not presented during training as a compound, but are paired separately with the unconditioned stimulus (light–US and tone–US pairings, respectively), the intra-LA infusion of anisomycin after the retrieval of the light does not affect the freezing to the tone during LTM. Top panel: chart showing the experimental design. Left graph: freezing to the light (mean ± SEM) of rats treated with ACSF or anisomycin during memory reactivation. Right graph: mean ± SEM freezing in response to the tone averaged across tone presentations during LTM. (T) Tone, (L) light, (US) unconditioned stimulus, (LTM) long-term memory, (ACSF) artificial cerebrospinal fluid, (Aniso) anisomycin, (*) P < 0.05 vs. ACSF group.
