{"id":{"repo_id":"wvu","oai_identifier":"oai:researchrepository.wvu.edu:etd-1624"},"canonical_url":"https://search.dev.ndltd.org/etd/wvu/oai:researchrepository.wvu.edu:etd-1624","repository":{"repo_id":"wvu","name":"West Virginia University","base_url":"https://researchrepository.wvu.edu/do/oai/"},"display":{"title":"Effects of Response-Independent Food Pellet Delivery on the Development of Tolerance to the Rate-Decreasing Effect of d-Amphetamine in Rats","abstract":"The extent to which initial drug administration decreases the ability of an organism to obtain reinforcement can affect the development of behavioral tolerance. Environmental enrichment affects many drug-related phenomena, but its effects on the development of tolerance are not clear. The present study examined how enriching the environment by providing non-contingent food pellets during experimental sessions affects the development of tolerance to a dose of d-amphetamine that produces a loss in reinforcement. Lever pressing for food pellets was maintained under a multiple schedule consisting of two variable-interval (VI) 60-s components. One component was enriched by providing food pellets non-contingently under a variable-time (VT) 120-s schedule for rats in the Less-Enriched Group (n = 6) and a VT 30-s schedule for rats in the More-Enriched Group ( n = 6). Effects of a range of doses of d-amphetamine (0.1 to 3.0 mg/kg) were assessed before (acute) and during (chronic) repeated injections of a dose that reduced the number of food pellets earned by at least 50% from sessions in which saline was tested acutely. There was a dose-dependent decrease in lever pressing, and relatively large doses were required to decrease the number of food pellets earned. Tolerance developed to a similar extent between components with and without non-contingent food pellets for rats in both groups. These results indicate that enriching the environment by providing non-contingent food pellets during experimental sessions does not differentially affect the development of tolerance.","abstract_html":"The extent to which initial drug administration decreases the ability of an organism to obtain reinforcement can affect the development of behavioral tolerance. Environmental enrichment affects many drug-related phenomena, but its effects on the development of tolerance are not clear. The present study examined how enriching the environment by providing non-contingent food pellets during experimental sessions affects the development of tolerance to a dose of d-amphetamine that produces a loss in reinforcement. Lever pressing for food pellets was maintained under a multiple schedule consisting of two variable-interval (VI) 60-s components. One component was enriched by providing food pellets non-contingently under a variable-time (VT) 120-s schedule for rats in the Less-Enriched Group (n = 6) and a VT 30-s schedule for rats in the More-Enriched Group ( n = 6). Effects of a range of doses of d-amphetamine (0.1 to 3.0 mg/kg) were assessed before (acute) and during (chronic) repeated injections of a dose that reduced the number of food pellets earned by at least 50% from sessions in which saline was tested acutely. There was a dose-dependent decrease in lever pressing, and relatively large doses were required to decrease the number of food pellets earned. Tolerance developed to a similar extent between components with and without non-contingent food pellets for rats in both groups. These results indicate that enriching the environment by providing non-contingent food pellets during experimental sessions does not differentially affect the development of tolerance.","abstract_has_math":false,"creators":["Krebs, Christopher A."],"institution":null,"degree_name":"PhD","degree_level":"Dissertation","degree_discipline":"Psychology","degree_department":null,"school":null,"contributors":["Karen G. Anderson","Stan Hileman","Steven Kinsey","Elizabeth Kyonka","Michael Perone"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-08-01T07:00:00Z","date_published":"2014-08-01T07:00:00Z","updated_at":"2026-07-24T06:14:46Z","subjects":["Behavioral sciences","Psychobiology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://researchrepository.wvu.edu/etd/621"],"render_values":[{"text":"https://researchrepository.wvu.edu/etd/621","href":"https://researchrepository.wvu.edu/etd/621","code":true}]}]},"links":{"outbound_url":"https://doi.org/10.33915/etd.621","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Karen G. 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Environmental enrichment affects many drug-related phenomena, but its effects on the development of tolerance are not clear. The present study examined how enriching the environment by providing non-contingent food pellets during experimental sessions affects the development of tolerance to a dose of d-amphetamine that produces a loss in reinforcement. Lever pressing for food pellets was maintained under a multiple schedule consisting of two variable-interval (VI) 60-s components. One component was enriched by providing food pellets non-contingently under a variable-time (VT) 120-s schedule for rats in the Less-Enriched Group (n = 6) and a VT 30-s schedule for rats in the More-Enriched Group ( n = 6). Effects of a range of doses of d-amphetamine (0.1 to 3.0 mg/kg) were assessed before (acute) and during (chronic) repeated injections of a dose that reduced the number of food pellets earned by at least 50% from sessions in which saline was tested acutely. There was a dose-dependent decrease in lever pressing, and relatively large doses were required to decrease the number of food pellets earned. Tolerance developed to a similar extent between components with and without non-contingent food pellets for rats in both groups. These results indicate that enriching the environment by providing non-contingent food pellets during experimental sessions does not differentially affect the development of tolerance."]},{"key":"dc:title","label":"Title","values":["Effects of Response-Independent Food Pellet Delivery on the Development of Tolerance to the Rate-Decreasing Effect of d-Amphetamine in Rats"]}]}],"canonical_facts":{"dc:contributor":["Karen G. Anderson","Stan Hileman","Steven Kinsey","Elizabeth Kyonka","Michael Perone"],"dc:creator":["Krebs, Christopher A."],"dc:date.available":["2019-01-17T08:00:00Z"],"dc:description.abstract":["The extent to which initial drug administration decreases the ability of an organism to obtain reinforcement can affect the development of behavioral tolerance. Environmental enrichment affects many drug-related phenomena, but its effects on the development of tolerance are not clear. The present study examined how enriching the environment by providing non-contingent food pellets during experimental sessions affects the development of tolerance to a dose of d-amphetamine that produces a loss in reinforcement. Lever pressing for food pellets was maintained under a multiple schedule consisting of two variable-interval (VI) 60-s components. One component was enriched by providing food pellets non-contingently under a variable-time (VT) 120-s schedule for rats in the Less-Enriched Group (n = 6) and a VT 30-s schedule for rats in the More-Enriched Group ( n = 6). Effects of a range of doses of d-amphetamine (0.1 to 3.0 mg/kg) were assessed before (acute) and during (chronic) repeated injections of a dose that reduced the number of food pellets earned by at least 50% from sessions in which saline was tested acutely. There was a dose-dependent decrease in lever pressing, and relatively large doses were required to decrease the number of food pellets earned. Tolerance developed to a similar extent between components with and without non-contingent food pellets for rats in both groups. These results indicate that enriching the environment by providing non-contingent food pellets during experimental sessions does not differentially affect the development of tolerance."],"dc:identifier":["https://doi.org/10.33915/etd.621","https://researchrepository.wvu.edu/etd/621"],"dc:subject":["Behavioral sciences","Psychobiology"],"dc:title":["Effects of Response-Independent Food Pellet Delivery on the Development of Tolerance to the Rate-Decreasing Effect of d-Amphetamine in Rats"],"thesis:degree_discipline":["Psychology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["PhD"]},"updated_at":"2026-07-24T06:14:46Z"}