In addition, one of the two outcomes (either pellets or sucrose) was delivered outside of the lever press-outcome contingency, i.e., in each second that no lever pressing occurred, either sucrose or pellets were delivered with the same probability (p[outcome/no action] = 0.05) that a lever press earned that outcome. As a result, the probability

SCH772984 cost of earning one of the two outcomes was the same whether the animal pressed the lever or not. The other action-outcome contingency was nondegraded because the rat was still required to press the lever to receive that outcome. For half of the animals, the lever press-pellet contingency was degraded, and the lever press-sucrose contingency remained intact. The remaining animals received the opposite arrangement. Rats were given two 20 min training sessions each day, one on each lever. Contingency Degradation Extinction Test. After the final day of contingency training, rats in both groups received a 10 min choice extinction test. During this test, both levers were extended and lever presses recorded, but no outcomes were delivered. Contingency Reversal Training. Subsequent to the contingency degradation extinction test, rats were trained to lever press on an RR-20 schedule with the previously trained contingencies reversed. That is, the lever that previously earned pellets now earned sucrose, and the lever that previously

earned sucrose now earned pellets. Contingency reversal training continued for 4 days. Devaluation Extinction check Tests. Devaluation extinction tests took place as described for outcome devaluation. Reinstatement AG-014699 in vivo Testing. Rats were retrained on the reversed contingencies on an RR-20 schedule for 1 day. The next day, an outcome-selective instrumental reinstatement test was conducted. The test session began with a 15 min period of extinction to lower the rats’

rate of responding on both levers. They then received four reinstatement trials separated by 7 min each. Each reinstatement trial consisted of a single delivery of either the sucrose solution or the grain pellet. All rats received the same trial order: sucrose, pellet, pellet, sucrose. Responding was measured during the 2 min periods immediately before (Pre) and after (Post) each delivery. The research reported in the manuscript was supported by grants from the National Institute of Mental Health MH56446, the National Health & Medical Research Council of Australia 633267, and a Laureate Fellowship from the Australian Research Council, FL0992409. The authors thank Amir Dezfouli for his comments on the manuscript. “
“Sensory-motor behavior requires a transformation between two very different representations of the desired movement. The sensory cortex contains “topographic” organizations of stimulus parameters such as the orientation of a visual stimulus or the frequency of a sound. Thus, different stimuli cause different groups of neurons to be highly active.