Date of Award

1-1-2010

Document Type

Campus Access Thesis

Department

Psychology

Sub-Department

Experimental Psychology

First Advisor

Rosemarie M. Booze

Abstract

One-trial object recognition (OR) is a popular paradigm for conducting stress-free studies of rodent recognition memory. Rodents' response to novelty depends upon complex interactions between intrinsic and extrinsic motivations, many of which decrease validity for measures operationally defining exploratory activity. Two such threats to validity include the frequency of non-exploratory behaviors exhibited during the retention phase of one-trial OR and the confounding of novelty preference with typical thigmotaxic activity in open field environments. Object motion may be employed to minimize the influence of these factors, thereby increasing the construct validity for novelty preference in this task. Prior to assessing the validity of a motion-based one-trial OR task, it is necessary to determine whether object motion is sensitive to novelty preference. Rats were subjected to either a standard or motion-based one-trial OR task from which measures of raw time exploration and discrimination were derived. Furthermore, object discrimination was assessed in male and female adolescent rats in order to characterize the sexual-dimorphism observed in rodent object recognition. Novel objects were explored significantly more than familiar objects in each task with motion-based OR demonstrating significant increases in exploration of both objects. Experiments 1 and 2 also showed that males explored the novel object significantly more than females. These results suggest that a motion-based one-trial OR task was sensitive to novelty preference in adolescent Sprague Dawley rats and may provide for enhanced construct validity in one-trial tests of object recognition.

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