Studies which have investigated the classical conditioning of various drug effects have almost exclusively employed a contextual or environmental cue as the conditioned stimulus (CS). One exception to this has been the use of gustatory cues in examining the aversive properties of drugs. The objective of this project is to investigate the ability of a gustatory cue to also serve as a CS when paired with the analgesic and locomotor effects of morphine. Rats will be given repeated presentations of a saccharin taste cue paired with morphine and then they will be tested for pain responsivity or locomotor activity following exposure to the taste cue alone. Pain sensitivity will be measured using a hot plate test and locomotion will be measured by counting photobeam interruptions in a chamber. The conditioned response (CR) will be characterized in different experiments by varying the drug dose used, the number of conditioning trials, and the delay between CS exposure and the behavioral test. Control experiments will be conducted in order to assess the possible influence of nonassociative mechanisms, as well as nongustatory CS elements, in the response obtained on the test day. This project will fill our gap in knowledge about the selective associations that a gustatory CS can make with different properties of a drug such as morphine.
