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. Author manuscript; available in PMC: 2013 Jan 1.
Published in final edited form as: Behav Brain Res. 2011 Sep 8;226(1):340–344. doi: 10.1016/j.bbr.2011.09.003

Figure 2. Rats previously exposed to conditions of uncertain reinforcement (VR) show significantly enhanced locomotor responding to a threshold dose of amphetamine (0.5 mg/kg, IP) compared to rats exposed to predictable reinforcement (FR).

Figure 2

Testing was conducted two weeks after the last VR or FR reinforcement exposure session. Rats were first injected with saline and three hours later with amphetamine. Data are shown in A as group mean (± SEM) locomotor counts observed throughout the 3-hr saline and amphetamine sessions. Group mean (+ SEM) total locomotor counts observed in the three hours after saline or after amphetamine are shown in B. Post-hoc Sheffé comparisons confirmed that amphetamine significantly enhanced locomotor responding in VR rats compared to saline (*p<0.01) and that this effect was enhanced in VR relative to FR rats (*p<0.01). n=5–6/group.