Asymmetrical dissociation of learning between scopolamine and Wy 4036, a new benzodiazepine tranquilizer

Hungry rats, trained to drink milk rapidly in a small test chamber, received a single electric shock 30 min after injections of either scopolamine, a new benzodiazepine tranquilizer (Wy 4036), or saline. One week later, subgroups were tested for conditioned suppression of the drinking response under all drug conditions, according to a factorial design. Conditioned suppression transferred from saline to both drugs, across the same drug, and from scopolamine to Wy 4036, but not from the drugs to saline or from Wy 4036 to scopolamine. All groups tested under Wy 4036 showed supernormal suppression. The pattern of asymmetrical transfer was explained by a hypothetical neural conditioning model. The supernormal suppression caused by Wy 4036 was attributed to enhanced retrieval of the memory of the shock experience.