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. 2006 Feb 8;26(6):1872–1879. doi: 10.1523/JNEUROSCI.4895-05.2006

Figure 2.

Figure 2.

Nicotine self-administration in P and NP rats. a, b, Mean ± SEM number of nicotine infusions and active lever responses during the first 24 d of nicotine self-administration (0.03 mg/kg per infusion) under FR-1, FR-2, and FR-5 reinforcement schedules. c, d, Mean ± SEM number of nicotine infusions and nicotine intake (milligrams per kilogram); data are from the dose–response determination during days 25–33 of nicotine self-administration training (3 d per dose). *Different from the NP group; p < 0.05 (Newman–Keuls post hoc test); n = 9–12 per line.