Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Psychology

Faculty/School

Faculty of Science

First Advisor

Linda Parker

Advisor Role

Thesis Supervisor

Abstract

The terms conditioned taste aversion and conditioned taste avoidance are often used interchangeably in the literature; however considerable evidence indicates that they may represent independent processes. Recent studies have demonstrated that conditioned taste aversion is mediated by conditioned sickness; however the mechanism(s) responsible for the establishment and expression of conditioned taste avoidance remains unknown. An early theory suggests that a taste that has been previously paired with a drug produces avoidance of that taste because it elicits some novel change in physiological state which signals danger to the rat. The emotional state produced may be one of conditioned fear. The present experiments evaluated the effect of exposure to a drug-paired flavor on avoidance of open arms in the elevated plus maze, an index of fear. If conditioned taste avoidance is mediated by conditioned fear, exposure to a drug-paired flavor should potentiate a rat’s fear reaction to the open arms of an elevated plus maze. In Experiment 1, rats were exposed to an amphetamine (3 mg/kg)- or lithium (25 mg/kg)- paired saccharin solution by bottle just prior to a test in a novel plus maze. Experiment 2 was conducted in a similar manner as Experiment 1, except rats were tested in a familiar plus maze. In Experiment 3, lithium-paired flavor was delivered by intraoral infusion prior to and during plus maze testing. Finally, in Experiment 4, rats were conditioned with 130 mg/kg of lithium and tested by intraoral infusion of saccharin solution l5 min prior to and during plus maze testing. In Experiments 2 and 3, when the CS flavor was delivered by bottle or intraoral infusion immediately prior to plus maze testing, the rats in the CS+ groups exhibited an increase in open arm activity compared to CS’ groups. However, when the CS flavor was delivered during plus maze testing, as in Experiments 3 and 4, rats in the CS+ groups exhibited increased avoidance of the open arms compared to rats in the CS‘ groups. The opponent process model may account for the pattern of results found here. The presentation of the CS flavor may have produced a state of fear (the a process), however upon termination of the CS flavor, the opposite emotional state, relief may have been revealed (the b process).

Convocation Year

2003

Convocation Season

Fall

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