Percent of total responses on the nicotine-appropriate lever (mean ± SEM) and overall response rate (total responses/sec) following s.c. injection of nicotine alone or extract in Experiment 3a (0.4 mg/kg nicotine training dose, A and B) and Experiment 3b (0.1 mg/kg nicotine training dose, C and D). * Significantly different from saline (0 mg/kg), p < 0.05 or 0.01. # Significantly different from nicotine alone at that dose, p < 0.05. For clarity, significant main effects of formulation (extract versus nicotine alone) in Fig 2A and 2C are not shown.