Recently, we reported that bilateral gustatory cortex (GC) lesions significantly impair taste sensitivity to salts in rats. Here we sought to extend the range of tastants tested to include sucrose and quinine in rats with ibotenic acid-induced lesions in GC (GCX) and in sham-operated controls (SHAM). Presurgically, on a single occasion, immediately after drinking 0.1 M NaCl (15 min), rats received either a LiCl or saline injection (i.p.), but postsurgical tests indicated a weak conditioned taste aversion (CTA) even in the SHAM LiCl-injected rats. The rats were then trained and tested in a gustometer to discriminate a tastant from water in a two-response operant taste detection task. Psychometric functions were derived separately for each tastant (sucrose, KCl, and quinine, in series) by lowering the stimulus concentration across test sessions. A mapping system was used to determine, in a blinded fashion, acceptable placement, size and symmetry of the bilateral lesions (~91% damage to GC on average). For KCl, there was a significant difference between GCX (n=22) and SHAM (n=13) rats indicated by a rightward shift (ΔEC50=0.57 log10 units, p<0.001) in the psychometric function, replicating our prior work. There was a significant lesion-induced impairment (ΔEC50=0.41 log10 units; SHAM [n=12], GCX [n=19], p=0.006) in quinine sensitivity as well. After taste sensitivity testing, a postsurgical CTA to a glucose polymer mixture, Maltrin, was trained in two conditioning trials and was then tested in a brief-access and 46-hr two-bottle preference test. The GCX rats displayed compromised CTA expression in the brief-access taste test, which focuses on orosensory characteristics of the tastant, whereas there was no deficit in CTA expression between surgical groups in the 46-hr preference test, which can be influenced by postingestive and olfactory factors. CTA was used here as a functional measure of the lesions as there is evidence in the literature that GC damage can impair CTA expression. Although taste sensitivities to KCl and quinine were attenuated, impairment with one stimulus was not significantly correlated with that of the other. Interestingly, unlike what was observed for KCl and quinine, taste sensitivity to sucrose was comparable between GCX (n=25) and SHAM (n=13) rats. Apparently, the degree to which the GC is necessary for the maintenance of normal taste detectability depends on the chemical and/or perceptual features of the stimulus. / A Thesis submitted to the Department of Psychology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2015. / February 11, 2015. / Animal Psychophysics, Gustatory Cortex, Taste Sensitivity / Includes bibliographical references. / Alan Spector, Professor Directing Thesis; Frank Johnson, Committee Member; Rick Wagner, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_252921 |
| Contributors | Bales, Michelle (authoraut), Spector, Alan C. (professor directing thesis), Johnson, Frank (committee member), Wagner, Richard K. (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Psychology (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (52 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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