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PubMed2001

Are human taste thresholds similar on the right and left sides of the tongue?

The human tongue is a relatively symmetrical anatomical structure and is generally assumed functionally equivalent on both sides. Experimental evaluation of this assumption is complicated by the fact that psychophysical measurements tend to vary considerably across testing sessions. To address functional laterality, we determined the detection thresholds of six right-handed and six left-handed subjects for Na saccharin, NaCl, citric acid and quinine HCl. Five pairs of interwoven, left and right unilateral thresholds were obtained for each taste stimulus in 12 subjects (n = 480 separate thresholds). In most cases mean sensitivity based on multiple measurements was found to be laterally symmetrical, however, we observed a few cases of lateral asymmetry of both general and compound-specific sensitivity. Threshold values were found to vary considerably across sessions, consistent with the test-retest variability previously reported for whole mouth thresholds. We conclude that taste threshold sensitivity is equivalent on the left and right anterior tongue for most individuals. Given the occasional exceptions to this rule, however, it is advisable to employ a counterbalanced design for any experimental or clinical testing protocol in which treatments are applied asymmetrically to the tongue.

Citric Acid↗
PubMed2004

Statistical comparison of the triangle test and the two-of-five test for taste and odor evaluation.

The Triangle test and 2-of-5 test are compared for their ability to evaluate tastes and odors in water and wastewater utilities. Both tests have varying statistical sensitivities. The 2-of-5 test is more sensitive and more powerful than the Triangle test, and generally requires fewer panelists for the same level of statistical confidence. This paper presents a method for determining the number of panelists for either test, and compares the results.

Environmental Monitoring↗
PubMed2005

The effects of modeling dietary restraint on food consumption: do restrained models promote restrained eating?

Sixty-nine female undergraduates completed the restraint scale, a dieting checklist, and the Eating Attribution Style Questionnaire (EASQ). The participants were exposed either to no model, a peer model who behaviorally demonstrated dietary restraint, or a peer model who behaviorally and verbally demonstrated dietary restraint. The participants had an opportunity to consume food as part of a taste test. The findings revealed that attribution style, but not restraint or current dieting status, moderated the effects of exposure to the peer models. Females who had an internal attribution style for indulgent food consumption decreased their consumption of food as a function of the dietary restraint of the models, whereas females who had an external attribution style for indulgent food consumption increased their consumption of food as a function of the dietary restraint of the models. The latter disinhibitory effect was attributed to negative social comparison and learned helplessness. The results supported the conclusion that the effectiveness of modeling dietary restraint is dependent on the attribution style of the observers.

Adolescent↗
PubMed1975

On the ultrastructure and permeability of taste buds of the marine teleost Ciliata mustela.

The abundant taste buds of the barbels and free fin rays of the five bearded rockling, Ciliata mustela contain an average of 100-150 cells, falling into two types. Tubule-containing cells ('t-cells'), tentatively identified as receptor cells, and each surrounded by fibril-containing cells ('f-cells') in the central part of the bud. t-Cells also occur in two concentric shells separated by indifferent epithelial cells at the periphery of the bud. f-Cells are characterized by their concentrations of fine fibrils, and by granules or vesicles of 180-190 mmu diameter. The 100 or so receptor cells in a taste bud are innervated by some 250 axons. Lanthanum penetrates more deeply into the extracellular space of taste buds than into the extracellular space of the general epithelium, perhaps indicating that a greater area than the mere protruding tip of receptor cells may be accessible to chemical stimulation. Degenerating cells may provide an important route of entry for such external agents.

Animals↗
PubMed2003

Dietary intake of older adults in the Kingston area.

The objectives of this research were to describe the dietary intake and identify risk factors for poor dietary intake in community-dwelling older adults living in the Kingston, Frontenac, and Lennox & Addington Health Unit area. Dietary intake information was collected from a convenience sample of 105 relatively healthy, active older adults (84 women, 21 men) using 24-hour recalls from three non-consecutive days. Risk factors for poor dietary intake were identified through a structured interview. Multiple linear regression was used to generate a model to predict dietary intake, which was measured using a diet score based on Canada's Food Guide to Healthy Eating. Group averages reflected reasonable diet quality, but some subjects had very low nutrient intakes, particularly of zinc and vitamins B6, B12, and C. On average, women had a lower-than-recommended intake from all food groups, while men consumed adequate amounts of all food groups except milk products. Higher scores indicated better overall diet quality, and the following were significant predictors of a high diet score: "almost always" preparing one's own meals, food "almost always" or "sometimes/never" tasting good, eating lunch every day, and taking fewer prescription medications. This model requires validation with a larger and more diverse population of community-dwelling older adults.

Aged↗
PubMed2001

fMRI activation in response to odorants orally delivered in aqueous solutions.

During food intake flavor perception results from simultaneous stimulation of the gustatory, olfactory and trigeminal systems. Olfactory stimulation occurs mainly through the retronasal pathway and the resulting perception is often interpreted as a taste perception, thus leading to the well-known sensory confusion between taste and olfaction. The present experiment was designed to study, with functional magnetic resonance imaging (fMRI), the cortical representation of olfactory perception in humans in response to retronasal stimulation by odorants delivered in aqueous solution. Psychophysical evaluation confirmed that the stimuli acted as pure olfactory stimuli through the retronasal pathway and did not present any taste component. Results showed activation in all brain regions previously described with neuroimaging techniques using olfactory stimulation with an odorized air flow. Piriform and orbitofrontal cortex were found activated as well as the hippocampal region, the amygdala, the insular lobe, the cingulate gyrus and the cerebellum. These results demonstrate the feasibility of efficiently stimulating the olfactory system in an fMRI scanner through the retronasal pathway with liquids delivered to the oral cavity. The presentation of olfactory stimuli in liquids to the mouth is a realistic model for the study of food-related flavor perception. This stimulation protocol furthermore allows presenting taste and olfactory stimuli separately or combined, thus allowing for direct comparisons between single modality representation, taste or olfaction, and representation of multi-modality mixtures.

Administration, Oral↗
PubMed1998

Telencephalic ascending gustatory system in a cichlid fish, Oreochromis (Tilapia) niloticus.

Central fiber connections of the gustatory system were examined in a percomorph fish Oreochromis (Tilapia) niloticus by means of the horseradish peroxidase (HRP), biocytin, and carbocyanine dye tracing methods. The primary gustatory areas in tilapia are the facial, glossopharyngeal, and vagal lobes of the medulla. The secondary gustatory nucleus (SGN) is a dumb-bell-shaped structure located in the isthmic region. In the SGN, there are two or three layers of neurons lining the ventromedial periphery of the nucleus and a molecular layer constituting of the major part of the nucleus. The SGN receives bilateral projections from the facial lobes and ipsilateral projections from the glossopharyngeal and vagal lobes. Ascending fibers originating from the SGN form the ipsilateral tertiary gustatory tract. A major part of the tract courses rostrally and terminates ipsilaterally in several diencephalic nuclei: the preglomerular tertiary gustatory nucleus (pTGN), the posterior thalamic nucleus, the nucleus diffusus lobi inferioris, the nucleus centralis of inferior lobe, and the nucleus recessus lateralis. The remaining small fiber bundle enters the medial and lateral forebrain bundles and terminates directly in two telencephalic regions; the area ventralis pars intermedia (Vi) and the area dorsalis pars posterior (Dp). Ascending fibers from the pTGN pass through the lateral forebrain bundle and terminate ipsilaterally in the dorsal region of area dorsalis pars medialis (dDm) of the telencephalon. Following biocytin injections into the dDm, small, round cells were labeled in the pTGN. After biocytin injections into the Vi and Dp of the telencephalon, retrogradely labeled cells were found in the ipsilateral SGN. The results show that the ascending fiber connections of the central gustatory system in the percomorph teleost tilapia are essentially similar to those of mammals. That is, the pathway from the primary gustatory areas (facial, glossopharyngeal, and vagal lobes) through the SGN and pTGN to the dDm in tilapia corresponds with the mammalian gustatory pathway from the solitary nucleus through the pontine taste areas (nucleus parabrachialis) and the thalamic relay nucleus (ventral posteromedial nucleus) to gustatory neocortices. In addition, the pathway from the primary gustatory areas through the SGN to the Vi and Dp in tilapia corresponds with the pathway from the solitary nucleus through the pontine taste areas to the amygdala in mammals.

Afferent Pathways↗
PubMed2001

Scanning electron-microscopic view of the oral and basal epithelial surfaces of the rat soft palate.

We studied corresponding structures on the oral and basal surfaces of the oral epithelial layer, focusing on the microanatomy of gustatory papillae. Specimens for scanning electron microscopy were obtained from the rat soft palates and fixed with a mixture of 2% paraformaldehyde and 1% glutaraldehyde. They were first prepared without postfixation and conductive-staining to study the oral surface. After examination, the epithelium was reinforced by additional sputter coating and treated with 6 N NaOH at 60 degrees C to exfoliate the basal epithelial surfaces without any significant artifacts. The papillae, showing circular, elliptical or fusiform protuberances on the oral surface, were classified into two types: types I and II. The type I and type II papillae contained one and two taste pores, respectively. On the basal epithelial surface, the basal portions of the taste buds were associated with concentrically arranged nerve fibers and Schwann cells. Another characteristic finding on the basal epithelial surface was the presence of excretory ducts of minor salivary glands in a close spatial relationship to taste buds. It is suggested that saliva coming out through the duct is mixed with food, thus enabling intimate contact with the taste pores of the papillae.

Animals↗
PubMed1995

The perception of saltiness is eliminated by NaCl adaptation: implications for gustatory transduction and coding.

The tastes of salts to humans are complex. NaCl is the most purely salty of all salts, but even this stimulus tastes sweet at low concentrations and somewhat sour at mid-range intensities. Other salts taste significantly sour or bitter in addition to salty. Previous studies have shown that the saltiness of simple halide salts is reduced by adaptation to NaCl, suggesting that a single mechanism might be responsible for the salty taste of these stimuli. In electrophysiological studies in rodents, the response to NaCl is reduced by application to the tongue of the Na(+)-channel blocker amiloride. Organic Na+ salts are more heavily dependent on this amiloride-sensitive transduction component than NaCl, and are generally less salty and more sour. In order to investigate the relationship between NaCl saltiness and that evoked by other salts, we adapted the tongue to distilled H2O and to 0.1 M NaCl and obtained direct magnitude estimates of the taste intensity of 15 organic and inorganic Na+, Li+, K+ and Ca2+ salts, matched for total intensity. Subjects divided these magnitude estimates among the component taste qualities. Adaptation to NaCl abolished the taste of NaCl and LiCl, and eliminated the saltiness of all other salts. The magnitude estimates of the bitterness and sourness of many salts increased after NaCl adaptation. Since recent biophysical data suggest that adaptation in taste receptors may involve whole-cell mechanisms, we propose that saltiness is reduced by NaCl adaptation because it originates in the subset of taste receptors responsive to NaCl. This implies that saltiness is coded within the CNS in cells whose receptive fields include the NaCl-sensitive receptor cells and that the degree to which any salt tastes salty is determined by its ability to drive these receptors. This model proposes, for example, that KCl has a salty component because it stimulates some of the same receptor cells as NaCl, even though the transduction mechanisms for KCl are different than those engaged by NaCl. Adaptation to NaCl blocks the saltiness of KCl and other salts because they stimulate NaCl-sensitive receptor cells.

Adaptation, Psychological↗
PubMed2001

Peptide property modeling by Cluj indices.

The novel Cluj property indices are used for modeling the biological properties of dipeptides: the ACE inhibition activity of a set of 58 dipeptides and the bitter tasting activity of a set of 48 dipeptides, taken from the literature. The results are compared to those reported in some previous works.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

Bitter-sweet solution in taste transduction.

A contentious issue in taste research might have come to a close. Zhang et al., in this issue of Cell, provide broad support for the notion that the recognition of sweet, umami, and bitter tastes use the same signaling molecules. Moreover, they show that individual taste cells are dedicated to the transduction of only one of these three taste qualities.

Animals↗
PubMed2006

Quantitative studies, taste reconstitution, and omission experiments on the key taste compounds in morel mushrooms (Morchella deliciosa Fr.).

Sensory-directed fractionation of an aqueous extract prepared from morel mushrooms led to the identification of gamma-aminobutyric acid as the chemical inducer of the mouth-drying and mouth-coating oral sensation imparted by morels. Additionally, L-glutamic acid, L-aspartic acid, succinic acid, and the previously unknown (S)-malic acid 1-O-beta-D-glucopyranoside, coined (S)-morelid, were detected as additional important umami-like taste compounds. To further bridge the gap between pure structural chemistry and human taste perception, 33 putative taste compounds were quantified in an aqueous morel extract and then rated for their taste contribution on the basis of dose-over-threshold factors. To confirm these quantitative results, an aqueous taste reconstitute was prepared by blending aqueous solutions of 16 amino acids, 6 organic acids, 3 purines, 4 carbohydrates, 3 minerals, and (S)-morelid in their "natural" concentrations. Triangle tests revealed that the taste profile of this biomimetic organoleptic cocktail did not differ significantly from the taste profile of authentic morel extract. To finally narrow down the number of key taste compounds, taste omission experiments were performed demonstrating that (S)-morelid together with L-glutamic acid, L-aspartic acid, malic acid, citric acid, acetic acid, and gamma-aminobutyric acid are the key organoleptics of morel extract. Moreover, sensory experiments with model solutions showed that (S)-morelid not only imparts a sour and umami-like taste but is able to amplify the taste activity of monosodium glutamate, as well as sodium chloride, solutions.

Adult↗
PubMed1994

[Sex dimorphism in the formation and extinction of aversion acquired to known and unknown tastes].

One group of Wistar rats were taught to consume 0.2% solution of saccharin up to stable preference of the latter to water. The aversion was established by means of an angle acceleration rotation. This was preceded by feeding the saccharin solution unfamiliar to the second group of rats. The aversion formed more obviously in the second group animals. The data obtained is discussed from the standpoint of sexual characteristics of the taste preference, defence behaviour, ecological specifics of interaction of males and females with ambient milieu.

Acceleration↗
PubMed1994

Motivational properties of ethanol in mice selectively bred for ethanol-induced locomotor differences.

Ethanol-induced locomotor stimulation has been proposed to be positively correlated with the rewarding effects of ethanol (Wise and Bozarth 1987). The present experiments provided a test of this hypothesis using a genetic model. Three behavioral indices of the motivational effects of ethanol (drinking, taste conditioning, place conditioning) were examined in mice from two independent FAST lines, selectively bred for sensitivity to ethanol-induced locomotor stimulation, and mice from two independent SLOW lines, selectively bred for insensitivity to ethanol-induced locomotor stimulation. In a single-bottle procedure, mice were allowed access to drinking tubes containing ethanol in a concentration (1-12% v/v) that increased over 24 consecutive days. FAST mice consumed greater amounts of ethanol solution. In a two-bottle procedure, mice were allowed access to tubes containing water or various concentrations of ethanol (2-8% v/v) over 6 days. FAST mice generally showed greater preference for ethanol solutions than SLOW mice. In a conditioned taste aversion procedure, mice received access to saccharin solution followed by injection of 2.5 g/kg ethanol (IP). SLOW mice developed aversion to the saccharin flavor more readily than FAST mice. In a series of place conditioning experiments, tactile stimuli were paired with various doses of ethanol (0.8-2.0 g/kg). During conditioning, FAST mice showed locomotor stimulation after 1.0, 1.2 and 2.0 g/kg ethanol while SLOW mice did not. During testing, mice conditioned with 1.2 g/kg and 2.0 g/kg ethanol showed conditioned place preference, but there were no line differences in magnitude of preference. These results indicate that genetic selection for sensitivity to ethanol-stimulated activity has resulted in genetic differences in ethanol drinking and ethanol-induced conditioned taste aversion but not ethanol-induced conditioned place preference. Overall, these data provide mixed support for the psychomotor stimulant theory of addiction.

Alcohol Drinking↗
PubMed1999

Effect of blanching time and salt concentration on pectolytic enzymes, texture and acceptability of fermented green beans.

Effect of blanching time, salt concentration and fermentation on texture of green beans (var. Tuf) was determined. Beans were blanched at 90 degrees C for 1, 10 or 20 minutes and fermented with brine containing 3.08 and 4.6% salt (corresponding to 1.2 and 1.8% salt in the finished product). The beans were assessed for texture mechanically using Universal Testing Machine (Model 1011, Instron). Sensory evaluation was carried out to assess the taste, texture and overall acceptability of the products. Pectolytic enzyme (pectinestarase and exopolygalacturonase) activities were determined in fresh and fermented beans. Increase in blanching time improved the texture significantly. Significant (p<0.05) decreases in shearing energy of the beans were observed in the first two days of fermentation and, thereafter, there were no significant (p>0.05) changes except for samples blanched for one minute. Salt concentration showed a small but significant effect on texture only in samples blanched for one minute and this was probably due to activation by salt of residual pectolytic enzymes in the beans. Most acceptable beans were those blanched for 20 minutes and fermented with 1.2% salt brine.

Carboxylic Ester Hydrolases↗
PubMedDate not supplied

A case-control study of gallstones: a major risk factor for biliary tract cancer.

Because of the strong association between gallstones and biliary tract cancer, we conducted a case-control study of gallstones at Niigata Cancer Center Hospital. Eighty-six cases with gallstones (33 males and 53 females) and 116 hospital controls (56 males and 60 females) were surveyed by means of a self-administered questionnaire. Gallstones were categorized into cholesterol stones (25 cases) and pigment stones (30 cases) based on the appearance of the stones. In multivariate analyses based on an unconditional logistic regression model, the risk of total gallstones was positively associated with a taste for salty food (relative risk (RR) = 2.31, 95% confidence interval (CI): 1.10-4.84), an intake of lettuce and cabbage (RR = 2.98, 95% CI: 1.47-6.06) and a family history of biliary diseases (RR = 5.63, 95% CI: 1.76-17.95), and inversely associated with an intake of salted and dried fish (RR = 0.16, 95% CI: 0.04-0.64). When analyzed by type of stones, cholesterol stones were associated with a taste for oily food (RR = 3.87, 95% CI: 1.36-11.03) and pigment stones were positively associated with professional or administrative occupation (RR = 4.74, 95% CI: 1.35-16.68) and inversely associated with a taste for less greasy food (RR = 0.28, 95% CI: 0.10-0.83). Some of these results are consistent with the results of our previous study on biliary tract cancer.

Adult↗
PubMed2006

Adolescent rats are protected from the conditioned aversive properties of cocaine and lithium chloride.

In humans, most drug use is initiated during adolescence and adolescent users are more likely to become drug-dependent than adult users. Repeated, high levels of use are required for the transition from use to addiction. Individual levels of drug use are thought to result from a balance between the pleasant or rewarding and the unpleasant or aversive properties of the drug. Repeated high levels of drug use are required for the transition from drug use to dependence. We hypothesized that diminished aversive effects of drugs of abuse during adolescence might be one reason for higher rates of use and addiction during this phase. We therefore tested adolescent and adult CD rats in single-dose cocaine conditioned taste aversion (CTA) at a range of doses (10-40 mg/kg), and examined whether various behavioral markers of addiction vulnerability were correlated to outcome in cocaine CTA. We found that adolescents are indeed less susceptible to cocaine CTA. In fact, age was the predominant predictor of CTA outcome, predominating over measures of novelty-seeking, anxiety, and stress hormone levels, which are all known to be related to drug intake in other models. Furthermore, we found that adolescent rats are also less susceptible to conditioned taste aversion to a low dose of a non-addictive substance, lithium chloride. These results suggest that one explanation for elevated drug use and addiction among adolescents is reduced aversive or use-limiting effects of the drugs. This contributes to our understanding of why adolescence is a particularly vulnerable period for development of drug abuse.

Aging↗