Year: 2006
Type: dissertation
Abstract: The aim of the present series of experiments was to outline the influence of\ndifferent doses of cocaine during training, training schedule, training length and\nabstinence duration to modulate subsequent extinction and reinstatement patterns.\nAbram Amsel’s general theory of persistence were used to both design and explain\nvarious aspects of these models.\nFor Experiment 1, rats self-administered cocaine (0.25, 0.50 or 1.00 mg/kg)\nintravenously and were then tested in an extinction preparation using saline infusions (5\ndays) and then only the stimulus light as the reinforcer (3 days). Experiment 2 examined\nschedules by magnitude interactions by training rats on two fixed-ratio (FR) schedules\n(FR-1 or FR-10 using either 0.25 or 1.00 mg/kg cocaine). Animals were tested in an\nextinction protocol (10 days; no stimulus light) and subsequently tested for reinstatement\n(1 day) that utilized presentations of the stimulus light. Experiment 3 addressed the\neffects of training length (15 or 30 days of training using either 0.25 or 1.00 mg/kg\ncocaine) using the same protocol as in Experiment 2. Experiment 4 examined the modulation potential of two abstinence lengths (15 or 30 days using either 0.25 or 0.50\nmg/kg cocaine) using the same conditions as Experiment 2.\nExperiment 1 indicated the greatest resistance to extinction using the lowest\ntraining dose (0.25 mg/kg). The removal of saline caused an apparent extinction burst\nindicative of reward seeking. Experiment 2 showed that animals trained under partial\nreinforcement schedules persisted more during extinction. Furthermore, rats trained\nusing 1.00 were more resistant than those trained with 0.25 mg/kg. Reinstatement of\ndrug seeking was more pronounced in rats trained using an FR-10 schedule. Experiment\n3 indicated greater resistance to extinction in rats trained for 15 versus 30 days. Rats\ntrained on 0.50 mg/kg for 30 days showed less cue-induced reinstatement than those\ntrained for 15 days. Experiment 4 showed increased resistance to extinction when rats\nwere trained on 0.25 mg/kg and forced to abstain for 30 versus 15 days. Directionally\nopposite effects were apparent in groups trained with 0.50 mg/kg. Reinstatement data\nindicated greater responsivity to cues by animals abstaining for 30 versus 15 days.
Author: Rodrigo Valles
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2306093435