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C D Parks

Publications and source records attributed to C D Parks.

4 recordsLinked to original sources
PubMed1999

Predicting relapse to cocaine-seeking behavior: a multiple regression approach.

Recovery of previously extinguished responding to stimuli paired with the administration of drugs of abuse is becoming a widely utilized animal model of relapse to drug-seeking behaviors. While this approach is useful for identifying factors such as conditioned stimuli that are associated with drug-seeking, it has not directly identified behaviors that might predict susceptibility to relapse. In this study, rats were initially screened for locomotor activity in response to a novel environment. Rats were then trained to self-administer cocaine. A stimulus light and tone were paired with each infusion of cocaine. After 14 days of self-administration (maintenance) rats underwent 7 days of extinction trials (extinction phase 1), in which responding yielded neither cocaine nor the presentation of the conditioned stimulus. After extinction phase 1, rats responded for presentations of the compound stimulus in the absence of cocaine (test day 1). Rats then underwent 3 more days of extinction (extinction phase 2). After extinction phase 2, rats were once again allowed to self-administer cocaine (test day 2) and received presentations of the compound stimulus. Hierarchical regression equations, utilizing data from locomotor screening and the average responding during maintenance and extinction phases 1 and 2, were then constructed in order to predict the magnitude of responding on test days 1 and 2. A model utilizing locomotor activity, maintenance responding and extinction phase 1 responding accounted for over 76% of the variance associated with responding on test day 1, with extinction phase 1 as best predictor. A further model indicated that locomotor activity was the best predictor of propensity to self-administer cocaine on test day 2. These regression models provide a novel approach to determining factors that may predict relapse to drug-seeking behaviors.

Animals↗
PubMed1997

Reciprocal strategies for large groups.

Reciprocal strategies have been shown to be effective in inducing long-term cooperation in social dilemmas involving small, but not large, groups. In this article, we argue that group-based reciprocal strategies (GBRS)--under which one reciprocates cooperative factions, not individuals, within the group--can induce cooperation in large groups. Results of two computer simulations of 100-member groups show that a GBRS accumulates a significantly larger payoff than do other commonly advocated mixed-motive strategies. A third simulation showed that the size of the cooperative faction is influenced by the nature of the payoff matrix; when there is considerable temptation to defect, one should cooperate only after a large number of others have done so, but if there is little temptation to defect, one should reciprocate the cooperative actions of a smaller faction. We also found that the use of a "win-cooperate, lose-defect" heuristic led to substantial total outcomes. Our results suggest several psychological factors are important in facilitating cooperation, yet need empirical study.

Journal Article↗
PubMed1989

Keratoconjunctivitis sicca with associated secondary uveitis elicited in rats after systemic xylazine/ketamine anesthesia.

The systemic administration of an anesthetic dosage of a combination of xylazine and ketamine hydrochloride produced an acute exposure keratopathy which progressed into a syndrome resembling keratoconjunctivitis sicca. Within a few minutes corneal changes occurred that were characterized by viscous mucus, loss of corneal luster and dryness. Other acute but transient changes included development of cataracts, mydriasis and proptosis. Progressive changes were observed in the cornea within 4 days which lasted at least 8 weeks in some cases, and included punctate epithelial keratopathy progressing to devitalized or keratinized epithelial plaques. Polymorphonuclear cell infiltration of the corneal stroma associated with plaques occurred. Epithelial denudation and neovascularization of the cornea, dilation and engorgement of iridial blood vessels, as well as flare in the anterior chamber were also seen. The ocular lesions induced by xylazine/ketamine should be considered carefully when designing or interpreting research on the anterior segment. Ketamine hydrochloride with sodium pentobarbital produced excellent anesthesia without any significant ocular side-effects and may be preferred in many instances.

Animals↗