THE GUSTATORY INSULAR THALAMOCORTICAL TRACT IS NECESSARY FOR ACQUISITION AND RETENTION OF DRUG-INDUCED REWARD COMPARISONS, BUT NOT LICL-INDUCED TASTE AVERSION

Open Access
Author:
Geddes, Rastafa I.
Graduate Program:
Neuroscience
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
January 05, 2009
Committee Members:
  • Patricia S Grigson Kennedy, Dissertation Advisor/Co-Advisor
  • Patricia Grigson, Committee Chair/Co-Chair
  • Ralph Norgren, Committee Member
  • Robert J Milner, Committee Member
  • Andras Hajnal, Committee Member
  • Robert G Levenson, Committee Member
  • Kevin Douglas Alloway, Committee Member
Keywords:
  • lesions
  • ibotenic-acid
  • primary taste cortex
  • conditioned taste avoidance
  • suppression
  • asymmetric
Abstract:
This dissertation systematic tested conditioned taste suppression (CTS) of a taste stimulus when repeatedly paired with morphine, cocaine, sucrose, or LiCl in male Sprague-Dawley rats with discrete lesions of the taste thalamus and/or insular primary gustatory cortex (GC). To begin addressing these ideas, we utilized stereotaxic-guided, ibotenic-acid lesions of the GC, or bilateral GCTx, in order to determine the role of the GC in CTS of a taste stimulus when contingently paired with morphine, cocaine, the emetic LiCl, and a known reinforcer such as sucrose (Chapters 2 and 3). At the end of Chapter 3, unilateral lesions of the primary GC was combined either an ipsilateral (Ip-CNTL) or a contralateral (THCx) electrophysiological-guided excitotoxic disruption of the taste thalamus, and tested under the successive negative contrast paradigm. In Chapter 4, rats with asymmetric THCx lesions were tested under drug contrast acquisition, retention, and LiCl-induced conditioned taste aversion (CTA). In Chapter 5, taste-drug induced CTSs were subsequently tested in naïve rats with THCx lesions under cocaine self-administration and cue-induced instrumental responding for morphine in the runway. Taken together, the results of our behavioral experiments suggest that the taste thalamocortical loop is essential for particular types of reward- and some forms of drug-induced CTS, but not innate preference/aversions, eliciting taste stimulated orofacial responses, producing LiCl-CTA or, an association between the taste CS and drug reward (i.g., cue-induced craving), per se. In Chapter 6, the interpretation our findings in terms of affective/cognitive perceptions as the driving forces behind (1) the possible the direction of sensory processing, (2) the manner in which relative value is attribution to relevant stimuli, and (3) the mode of by which behavioral responding (voluntary/autonomic) under specific CS-US pairings.