Graduation Year

2017

Document Type

Thesis

Degree

M.A.

Degree Name

Master of Arts (M.A.)

Degree Granting Department

Psychology

Major Professor

David Diamond, Ph.D.

Committee Member

Toru Shimizu, Ph.D.

Committee Member

Joseph Vandello, Ph.D.

Keywords

fear, anxiety, conditioning, Memory, inhibitory avoidance, predator

Abstract

Translational research provides a unique opportunity to investigate innate and conditioned fear to develop an integrated understanding of anxiety disorders, ultimately improving treatment for those afflicted. Many fear conditioning paradigms use physically aversive stimuli to induce fear but ethological stimuli may better represent psychological disorders from a translational standpoint. Natural predators and immobilization have been successful in inducing both innate and contextually conditioned fear in rodents but an inhibitory avoidance paradigm that uses ethologically relevant stimuli has yet to be developed. To expand the use of these stimuli into inhibitory avoidance conditioning, an inhibitory avoidance paradigm was developed to include a range of ethologically relevant psychologically (predator exposure, physical restraint) and physically aversive stimuli (electric shock). Adult male Sprague-Dawley rats were conditioned using a step-through inhibitory avoidance model to associate crossing between two compartments with the presentation of an aversive stimulus. Subjects were assessed for conditioned fear measured by crossing latency, freezing behavior and defecation during conditioning and a contextual memory test. Freezing behavior within the conditioning chamber remained constant throughout conditioning regardless of stimulus but all groups conditioned with an aversive stimulus showed significant increases in crossing latency both overtime and during the retention test compared to subjects that received no aversive stimulus after crossing, indicating that inhibitory avoidance conditioning was achieved. Significant increases in defecation were also observed for footshock and predator exposed animals and this effect was intensified by predator exposure, but only after repeated exposures. With this, both predator based and restraint-based variations of the inhibitory avoidance model (PBIA and RBIA, respectively) have been successfully established and have been shown to induce evidence of emotionality similar to those seen in traditional shock-based inhibitory avoidance (SBIA) models. Successful development of PBIA and RBIA expands the range of stimuli that can be used with conventional inhibitory avoidance models, allowing for investigation into topics that have yet to be addressed in inhibitory avoidance conditioning.

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