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. Author manuscript; available in PMC: 2010 Jul 2.
Published in final edited form as: Pharmacol Biochem Behav. 2008 Feb 8;89(4):508–514. doi: 10.1016/j.pbb.2008.02.004

Figure 2.

Figure 2

Mean (SEM) total number of active lever responses for Groups 0-mg (n=7) and 16-mg (n=7) at each methamphetamine dose (mg/kg) tested during the progressive-ratio procedure (Experiment 2). The asterisk indicates that control and lead-exposed animals were significantly different (p<0.05).