AcknowledgementsThis study was supported by the National Basic Research Program grants from the Ministry of Science and Technology of China (No 2003CB515400 and No 2009CB522000), the National Science Fund for Distinguished Young Scholars from the National Natural Science Foundation of China (No 30425002) and the Chinese Academy of Sciences (No KSCXI/YW/R/68). We thank Aaron Ettenberg for helpful suggestions on runway behavior and Barry J Everitt for the heterogeneous chained schedule.
Aim: To evaluate the influence of an initial heroin experience under a modified two-chained training schedule on drug-seeking behavior after a long abstinence period. Methods: Rats were trained to respond for intr...