The Mexican tetra, Astyanax mexicanus, exists as two morphs of a single species, a sighted surface morph and a blind cavefish. In addition to eye regression, cavefish have an increased number of taste buds, maxillary teeth and have an altered craniofacial skeleton. I investigated the effect the lens has on the development of the surrounding skull by ablating the lens over early ontogeny. This unique long-term study sheds light on how early embryonic manipulations on the eye can affect the shape of the adult skull. The effects of lens ablation were analyzed using landmark based morphometric analyzes. Morphometric analyzes indicate that there is a significant difference in the shape of the supraorbital bone and suborbital bones four through six. These bones expand into the eye orbit exhibiting variability in their shape. Interestingly, the number of caudal teeth on the lower jaw is also affected by lens ablation. I compared these findings between morphs and across two teleost species. I conducted lens removal in the surface fish to determine if it would produce a cavefish phenotype. Lens removal in the surface fish only partially results in a cavefish phenotype, indicating that lens loss is not solely responsible for the phenotypic differences between the two morphs. The effects of lens removal were then compared in the Mexican tetra and zebrafish. Surprisingly, the results indicate that the same bones are variable in shape in both species, indicating that the variability of these bones is conserved across species. Finally, I compared laser lens damage and full lens removal, to investigate the capacity for both lens regeneration and healing in the Mexican tetra. Together, the lens healing and regeneration studies indicate that lens absence in early development does not influence the shape of the skull. Lens absence during later development influences the mechanical forces in the skull resulting in the bones of the orbital region changing in size and shape. This study highlights the dynamic nature of the skull and sheds light on the influence the eyes (a soft tissue) have on the surrounding skull (a hard tissue) a topic which has been overlooked in the literature.

This thesis investigated the perception of salt taste in two novel strategies for inclusion of NaCl in liquid foods: water-in-oil (w/o) emulsions and mucoadhesive biopolymer solutions. The major factors influencing w/o emulsion stability and perception were evaluated and a response surface model was developed. The amount of dispersed aqueous phase was the most significant factor affecting stability and perception. NaCl stabilized the emulsions and depressed salt sensory perception at elevated concentrations due to its interaction with the emulsifier polyglycerol polyricinoleate. Future research should elaborate events during oral processing of w/o emulsions. Biopolymer mucoadhesive character and concentration effects were also investigated. Mucoadhesion did not enhance salt taste. Above c*, there was a significant depression of sensory intensity, enhanced in polymers with hyperentanglements in solution. The depressive concentration effect may mask the effects of mucoadhesion. Future research should also inspect the influence of thickened hydrocolloid microstructure on perception. / The Advanced Foods and Materials Network

No description available.

Taste buds are spindle-shaped collections of taste receptor cells located in the surface epithelium of the oral cavity. Taste receptor cells are specialized sensory epithelial cells that are responsible for the transmission of taste information to the taste nerves. Immunocytochemical evidence of the neuropeptide cholecystokinin in various taste cells of the rat has been presented by our lab (Herness 1991). These results have prompted our investigation of the messenger RNA encoding this peptide in rat taste cells. CCK may play an important role in taste signal transmission or modulation.Three areas of the oral cavity were investigated for the presence of CCK mRNA. Two of these areas contain collections of taste buds in well-defined structures called papillae. Circumvallate papillae, located on the posterior surface of the tongue, and foliate papillae, located on the lateral surfaces of the tongue, were sectioned and probed for CCK mRNA using non-radiographic in situ hybridization. The third area investigated was the nasoincisor duct, located on the roof of the oral cavity. This duct contains isolated taste buds within the surface epithelium near the opening to the oral cavity.The results of this study confirm the presence of CCK mRNA in all three areas studied. Taste buds located in the circumvallate papillae, foliate papillae and in the nasoincisor duct all contain taste cells that express CCK mRNA. These results are verified by the absence of labeled cells in negative control experiments. The negative controls consists of the omission of probe, anti-DIG antibody, and the application of a sense probe. The immunocytochemical results show only a subset of taste cells labeled for the CCK peptide while the in situ results depict all cells in the bud labeled for CCK mRNA. The in situ results very closely parallel the immunocytochemical results previously obtained by our lab, although with in situ hybridization epithelial staining is more prominent. The surface epithelium contains the messenger RNA encoding CCK likely because taste receptor cells are derived from the lingual epithelium.Several roles for CCK can be considered in taste physiology. Taste reception and taste signal transduction is not fully understood. Also the localization and pharmacology of CCK receptors in taste systems awaits investigation. These two areas must be studied further to understand the function of CCK in taste cells. / Department of Biology

How do music consumers come into contact with the music they like? How is music consumption patterns developed? Using a phenomenological approach this master's thesis sets out to answer a number of questions regarding the development of music consumption patterns. To do this in-depth interviews has been carried out with eleven respondents who were interviewed about their experi- ences of developing a music consumption pattern. Through this research it is shown how the development of music consumption patterns is a long process which begins with the introduction of the music consumer to an artist or group upon which future consumption will be conditioned and continues through the constant adding of new music and knowledge until the music listener one day stops developing his or her taste further and the music consumption stagnates. This research has also made possible the analysis of how well three influential theoretical models are at explaining music consumption from the perspective of the music consumer.

No description available.

The aim of this doctoral dissertation was to examine effects of olfactory imagery on other sensory and perceptual processes, and to explore brain areas involved in generation of olfactory mental images. Four studies, three behavioral and one functional neuroimaging (Positron Emission Tomography, or PET), were conducted, and healthy volunteers participated in all four studies. In Study 1, participants were better at detecting weak odors when they simultaneously imagined the same compared with a different odor as the one being detected. This effect of olfactory imagery was specific, as the request to imagine objects visually did not have any effect on detection of weak odors. In Studies 2 and 3, effects of presented and imagined odors on taste perception were compared. Effects of imagined odors were equivalent to the effects of presented odors when an objective measure of taste perception (detection of a weak tastant, Study 3) was used, and comparable but more limited when a subjective measure of taste perception (intensity ratings, Study 2) was used. In Study 4, PET technology was used to investigate changes in cerebral blood flow (CBF) associated with odor imagery. Participants were screened and selected for their odor imagery ability, using the behavioral paradigm developed in Study 1. Increased CBF associated with odor imagery was revealed in several areas relevant for olfaction: the left primary olfactory cortical region including piriform cortex, the left secondary olfactory cortical region (posterior orbitofrontal cortex), and the rostral insula bilaterally. Interestingly, increased activity in the primary olfactory cortex and the rostral insula was observed both in the odor imagery and the odor perception subtraction. Based on the obtained findings, I concluded that the effects of imagined odors on sensory processes are specific when compared with visual imagery, and similar to the effects of presented odors. Furthermore, the neural

Food intake is regulated by both appetite and orosensory reward systems. Appetite systems stimulate or reduce hunger, while orosensory reward motivates consumption of high fat sweet foods, resulting in food enjoyment. The majority of advanced cancer patients suffer from malnutrition and wasting, which may be caused by a loss of appetite due to physiological changes or a hindered orosensory reward system due to taste and smell (chemosensory) changes or both. Orosensory reward systems were hypothesized to be impaired in advanced cancer. To understand the influence of chemosensory alterations on food intake and enjoyment, the nature (intensity) of chemosensory alterations in cancer patients and their relationship with ingestive behaviour and quality of life (QOL) were investigated (study 1). Advanced cancer patients (n=192) more frequently self-reported tastes and odours to be heightened rather than diminished (p=0.035). Patients with perceived chemosensory alterations had poorer QOL (p=0.0176) and lower caloric intake (p=0.0018) compared to patients with no alterations. Cannabinoids (e.g. -9-tetrahydrocannabinol, -9-THC) increase food intake by stimulating both appetite and orosensory reward systems as well as potentially enhancing chemosensory function. To palliate chemosensory alterations and poor appetite, advanced cancer patients (n=21, study 2) with these symptoms were randomized to receive either -9-THC (2.5mg) or placebo oral capsules twice daily for 18 days. Compared to patients receiving placebo, -9-THC-treated patients reported that food tasted better (p=0.04), they had improved chemosensory perception (p=0.026), increased preference and intake of high protein foods (p=0.008), and improved appetite (p=0.05), quality of sleep (p= 0.025), and relaxation (p= 0.045). Like cancer patients, tumour-bearing rats appeared to experience a loss of orosensory reward, showing tumour-associated anorexia when fed a rewarding diet to the same degree as on a usual diet (study 3). -9-THC significantly increased caloric intake compared to vehicle for both tumour-bearing (p=0.0146) and healthy rats (p=0.0004), suggesting endocannabinoid-mediated appetite systems are functioning in this tumour model. The findings of this thesis suggest orosensory reward systems to be impaired in advanced cancer, decreasing the liking and motivation to eat. -9-THC treatment may help to palliate perceived chemosensory alterations and loss of appetite and food enjoyment in advanced cancer. / Food Science and Technology

This thesis explored whether individual differences in taste perception (as measured by the rated intensity of 6-n-propylthiouracil (PROP)) were associated with tobacco use, alcohol use and misuse and obesity in the Dunedin Multidisciplinary Health and Development Study birth cohort at age 32. This cohort of 1037 participants was assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26 and, most recently, at 32 years, when 96% of the living study members were interviewed. At age 32, participants rated the intensity of a 0.0032mol/L solution of PROP using the general labelled magnitude scale (gLMS). PROP is almost tasteless to some but tastes bitter to others. As bitter tastes are aversive, due to their association with toxicity, it has been suggested that responses to PROP may reflect individual differences in taste perception that, in turn, have a protective effect on health. Study One sought to establish correlates of rated PROP intensity in this sample. A model controlling for sex, childhood socio-economic status (SES), childhood IQ and gLMS use predicted approximately 12% of the variability in PROP ratings. This finding highlighted the importance of using appropriate covariates in research attempting to link PROP perception with health risk behaviours, as these factors have also been associated with tobacco use, alcohol use and adiposity. Study Two did not find that greater perceived intensity from PROP was protective against smoking, as pack years smoked was not associated with PROP rating and ratings between groups of smokers were not significantly different. Differences in PROP perception were not protective against the lifetime smoking in this sample. Similarly, Study Three found no evidence to suggest that greater intensity from PROP was associated with reduced alcohol misuse. Furthermore, the previously observed association between PROP and yearly alcohol consumption may be better explained by the fact that SES accounts for some of the variance in both measures. In Study Four, rated PROP intensity was associated with Body Mass Index (BMI), waist circumference and body fat percentage, in women, but not in men. These associations were weakened after the inclusion of covariates in the models, but remained significant for both BMI and body fat percentage. Findings from Study Four indicate that taste perception may be associated with measures of adiposity in women. Taken together, these results highlight the importance of using appropriate control variables in research and indicate that a single measure of PROP perception may not adequately reflect the full effect of individual differences in taste perception on tobacco use or alcohol use and misuse. Since PROP perception was associated with differences in adiposity in women, however, individual differences in taste perception may be of public health importance. Future research should use continuous measures of a wider range of taste stimuli, to establish how taste perception (rather than just bitterness perception) affects health. Research should also ensure that covariates associated with tobacco use, alcohol use and misuse and adiposity (such as sex, SES and IQ) are included in analyses.

This thesis investigates whether fats, akin to other taste stimuli, exhibit sensory properties such as mixture interactions. In order to determine gustatory, rather than tactile or olfactory effects, viscosity-controlled emulsions of deodorised oils were used as the base to which taste stimuli were incorporated and presented to a panel of trained assessors. In preliminary qualitative assessments, panellists described the 10% olive oil emulsion as saltier, stronger, fattier and having a more lingering aftertaste than the non-oil control, suggesting that oil modulates taste duration as well influencing taste intensity and/or perceived quality. Panellists were unable to rate the oil/fat taste per se with any degree of certainty hence further experiments examined the effect of oil on the perception of taste mixtures. In mixture interaction experiments, the addition of oil did not result in mixture suppression or enhancement for sweet, salty, sour or bitter while it significantly enhanced umami. To determine the locus of interaction, when MSG and oil were presented to each side of the tongue separately, the enhancement effect disappeared indicating a peripheral mechanism of interaction, similar to the attenuation of chilli burn by oil. In contrast, suprathreshold sucrose sweetness was enhanced by the contralateral presentation of oil, indicating sensory processing at a higher locus. Furthermore, the addition of oil significantly reduced bitterness in a caffeine-MSG mixture. Since earlier experiments did not indicate any interaction between oil and bitterness, the decrease in the perceived bitterness of this binary mixture is attributed to an increase in umami which is likely to have suppressed bitterness, the perceptually dominant component in this mixture. These findings suggest a gustatory role for fats in modulating the taste profile of mixtures, in particular, enhancing total taste intensity, prolonging taste duration, and enhancing umami. A taste receptor-based model of fat perception provides for an orosensory mechanism capable of signalling the arrival of the most energy-dense nutrient, essential fatty acids and fat-soluble vitamins. The chemosensory signal may also be the basis for hedonic responses with subsequent implications for intake.