Date of Completion
Honors College Thesis
Dr. Donna Toufexis
methamphetamine, habit, sex-difference in habit
Operant conditioning is a type of learning where behaviors become more or less likely to reoccur after being rewarded or punished. Habits are motor responses performed automatically in response to a particular stimulus, which can be adaptive because it frees up cognitive workspace for other tasks. Habits form after repeated pairings of the behavior with a desirable outcome, and eventually the behavior will occur even when the outcome is no longer rewarding. The parallel to addiction is not coincidental, as substance abuse is thought to change the networks involved with habit. However, the neural circuitry underlying the transition in behavior from goal-directed to environment-elicited is not completely understood. Exposure to psychostimulants prior to training has been shown to decrease the number of reward exposures needed during operant training for an animal to begin to respond habitually rather than in a goal-directed manner. This study investigated the effect of pre-exposure to methamphetamine on Long Evans male rats with 120 and 160 response-reinforcer exposures on a variable-interval 30-s schedule, which is a level of reinforcement subthreshold to habit in male rats. Following pairing of the sugar-pellet reward with taste-aversive lithium chloride, the rate of responding (nose-poke behavior) for both the methamphetamine pre-treated and control groups showed that both were sensitive to reward devaluation. This implies that the methamphetamine pre-treatment did not accelerate habit formation at either level of training. This is a divergence from the literature which predicted that pre-exposure with psychostimulants would accelerate habit formation in males.
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Evans, Charlotte, "Effect of pre-exposure to methamphetamine in male rats at two training levels subthreshold to habit" (2020). UVM Honors College Senior Theses. 343.