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. Author manuscript; available in PMC: 2010 May 16.
Published in final edited form as: Behav Brain Res. 2008 Dec 14;199(2):326–333. doi: 10.1016/j.bbr.2008.12.011

Figure 3.

Figure 3

Modulation of investigatory behavior by several drugs. The top panel of graphs shows that peripheral administration of morphine (1 mg/kg i.p.) or naltrexone (1 mg/kg i.p.) alone or in combination reduced the amount of time spent in social investigation. Overall, the impact of opioid drugs was much greater on social investigation than on nonsocial exploratory activity. The bottom panel shows that peripheral administration of amphetamine (0.25 mg/kg i.p.) produced a robust facilitation of both social investigation and exploratory activity, but that the overall preference for the social hole was relatively intact. Haloperidol treatment (0.25 mg/kg i.p.) dramatically reduced activity at both holes irrespective of whether it was administered alone or in combination with amphetamine. All data are expressed as means ± SEM; an asterisk (*) indicates a significant difference between the groups indicated (p<.05).