Graduation Semester and Year

2014

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Psychology

Department

Psychology

First Advisor

Perry N Fuchs

Abstract

The misdirection of attention has been used to reduce experimental and clinical pain- a technique known as distraction analgesia (DA). A growing understanding of the important interrelationship between cognition and pain has prompted the need for a deeper understanding of its neural substrates. There is evidence implicating the infralimbic cortex of the rat brain as a putative mediator of DA, but this has never been directly tested. Therefore, this study investigated the role of the infralimbic cortex (IL) in a rat model of DA at high- and low-intensity pain. One hundred fifty two Sprague Dawley rats underwent stereotaxic surgery to receive either a bilateral electrolytic lesion to the IL or a sham procedure. Following recovery, rats underwent a week of daily habituation to a test chamber. Following habituation, rats received a subcutaneous injection of either .5% or 1% formalin into the plantar surface of the left hindpaw and underwent a formalin test in the same chamber to which they had been habituated. Each chamber was either left empty or outfitted with an inverted falcon tube to serve as a distractor. Behavior during habituation and formalin testing was recorded with tracking software. The presence of the distractor was associated with significantly decreased formalin pain scores in sham animals (p < .05), indicating successful DA. However, distractor presence did not decrease formalin pain scores in IL-lesioned animals, indicating that the IL lesion attenuated DA. The IL lesion was also found to reduce formalin pain scores relative to sham controls when tested in the empty chamber (p < .01), implicating a direct role for the IL in the processing of pain. Additionally, patterns in the data suggest that high-intensity pain may be more susceptible to DA than low-intensity pain. This study presents the first published evidence of the IL's role in pain processing and in distraction analgesia. Implications and future directions for studying the interplay between cognition and pain are discussed.

Disciplines

Psychology | Social and Behavioral Sciences

Comments

Degree granted by The University of Texas at Arlington

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