Skip to main content
. Author manuscript; available in PMC: 2015 Dec 22.
Published in final edited form as: Synapse. 2014 Jun 19;68(10):437–444. doi: 10.1002/syn.21755

Figure 1. Self-administration for rats responding under an FR5 for i.v. cocaine (250 μg/inf), heroin (10 μg/inf) or speedball (250/10 μg/inf cocaine:heroin).

Figure 1

Responding was engendered under an FR1 (and remained FR1 for saline controls) then increased to FR5. (A) Number of infusions per day (mean ± SEM). Speedball, cocaine and heroin self-administration resulted in a significantly greater number of infusions compared with saline across the thirty days. There was no significant difference in the number of infusions between the speedball, cocaine and heroin groups. (B) The average (mean ± SEM) inter-infusion interval was not significantly different between the groups. In addition, there was no significant difference in the inter-infusion interval between the groups across the 30 self-administration sessions.