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Type of Document Thesis Author Howard, Karilynn URN etd-09172003-221250 Title Conditioned Taste Aversion: Short-Term Expression And Neural Activation Degree Master of Science Department Biological Science, Department of Advisory Committee
Advisor Name Title Thomas A. Houpt Committee Chair Charles Ouimet Committee Member Laura Keller Committee Member Michael Meredith Committee Member Keywords
- Conditioned Taste Aversion (CTA)
Date of Defense 2003-08-02 Availability unrestricted Abstract Conditioned taste aversion (CTA) is a unique form of classical conditioning whereby an animal learns to associate a novel taste stimulus withnegative visceral effects. Acquisition of CTA results in reduced intake of future
presentations of the conditioned novel taste stimulus. Here I investigated both behavioral and neural characteristics of CTA expression in two experiments: 1)
taste specificity and learned safety of short-term CTA expression, and 2) whether
the same neurons that are activated during CTA expression against conditioned
sucrose (the CS) are re-activated by LiCl injection (the US). In the first
experiment, we tested whether short-term CTA expression shares with long-term
CTA expression the well-defined features of taste specificity to the conditioned
taste and learned safety (reduced association of a taste with a toxic effect by
prior non-toxic experience with the conditioned taste). We found that short-term
expression of CTA was not taste specific and could be attenuated by prior
exposure to the conditioned taste only. The second experiment investigated
activation at the neural level. CTA acquisition results in expression of c-Fos in
the intermediate zone of the nucleus tractus solitaris (NTS) following presentation
of the conditioned taste. These patterns of c-Fos expression are similar to what is
seen following administration of LiCl. By administering the conditioned taste 3
hours prior to the administration of LiCl, we were able to double-label for c-Fos
protein (induced by the taste and persisting after mRNA degradation ) and c-fos
mRNA (induced by the toxin prior to protein synthesis) and thus measure dual
activation of cells by the taste and the toxin. We found that approximately 40% of
cells expressing c-Fos were double-labeled for protein and mRNA.
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