Different aspects of the motivation to self-administer heroin and cocaine revealed by two progressive ratio schedules of reinforcement
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The motivation to self-administer heroin or cocaine was investigated using two different progressive ratio (PR) schedules of reinforcement. On the first schedule, the response requirements began at 1 and escalated systematically within the session. On the second schedule, the initial response requirements were adjusted according to the previous day's performance. Subsequent response ratios escalated exponentially. By comparing the breaking points derived from the two schedules, it was concluded that the motivation to self-inject cocaine increases with cumulative drug intake while the motivation to self-administer heroin decreases with each injection and is regulated by satiety. The ability of the second PR schedule of reinforcement to detect changes in the motivation to self-administer heroin was further investigated. Breaking points were shown to be sensitive to the opiate antagonist naltrexone. Heroin self-administration was shown to be remarkably resistant to extinction following saline substitution for heroin reinforcement although breaking points finally declined after several days. Finally, an inverted U-shaped dose-response relationship was established between breaking points reinforced with 12.5, 25, 50, and 100 |ig/inj unit heroin dose.
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This work is available on request. You can request a copy at https://library.carleton.ca/forms/request-pdf-copy-thesis
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Copyright © 1989 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, research, scholarship, and teaching. Theses may only be shared by linking to Carleton University Institutional Repository and no part may be used without proper attribution to the author. No part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.
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- 1989
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