Conditions for fear

摘要

State-dependent memories are those that are most successfully retrieved when conditions at the time of recall are the same as they were at encoding, but the mechanisms that lead to state-dependent learning are not known. Jovasevic et al. now show that activation of extrasynaptic GABA type A receptors (GABA_ARs) in the hippocampus immediately before training results in state-dependent fear conditioning, which is negatively regulated by microRNA-33 (miR-33). Administration of gaboxadol (GBX; a GABA_AR agonist) to the hippocampus in mice just prior to fear-conditioning training (in which mice were placed in a novel context, and received a footshock) decreased freezing (a measure of the fear response) when the mice were tested 24 hours later in the same context.