Figure 4

Panels (A,B): mean (SEM) DRs from sample and choice phases of rats (n = 37) on the test of memory modulation by self-administration sessions 1 and 6, respectively. Panel (C): mean (SEM) DRs from sample and choice phases of FR1 only (n = 16), No SCH (n = 18), 0 SCH (n = 10), and 0.10 SCH (n = 9) groups on the test of memory modulation by the 12th session of heroin self-administration. The * indicates a significant difference between phases.