Contextual Fear Conditioning in Mice

Immediately after the NOR task was finished, mice underwent cued and contextual fear conditioning, as previously described (Matousek et al., 2010 (link)). Briefly, on conditioning day, mice were allowed to explore the conditioning context, which consisted of a Plexiglas chamber and metal floor grid. After 3 min, 15 s of white noise was presented co-terminating with a 2 s, 0.75 mA foot shock. This noise-shock pairing was repeated twice for a total of 3 shocks with a 30 s interval between shocks. Twenty-four hours later, mice were re-exposed to the conditioning chamber for 5 min each to test long-term contextual memory. Four hours later, mice were placed in a novel context consisting of a 15 cm open-topped plastic cylinder with bedding on the floor for 3 min followed by re-exposure to the white noise for 3 min, to test hippocampal-independent memory. All data were video recorded and analyzed by FreezeView Software (Coulbourn Instruments).