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. Author manuscript; available in PMC: 2009 Jun 8.
Published in final edited form as: Pharmacol Biochem Behav. 2007 May 5;87(2):267–279. doi: 10.1016/j.pbb.2007.04.023

Figure 2.

Figure 2

Responding for cocaine delivered on a behaviorally demanding PR2 schedule for the same 4 groups of mice shown in Figure 1. Symbols are as described for Fig 1. (A) The mean ± S.E.M. across 4 sessions on PR2 was elevated in comparison to response output on the FR2 schedule. (B) The 2 level hierarchical model predicted values for lever pressing across sessions for the same mice. The analysis indicated that responses for the 0.3 mg/kg unit dose of cocaine were greater for male than for female mice and responses where similar between the sexes for the 1 mg/kg cocaine unit dose.