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Results for “Taste modeling”

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PubMed1967

Mach band type lateral inhibition in different sense organs.

Experiments were done on the skin with shearing forces, vibrations, and heat stimuli and on the tongue with taste stimuli to show that the well known Mach bands are not exclusively a visual phenomenon. On the contrary, it is not difficult to produce areas of a decreased sensation magnitude corresponding to the dark Mach bands in vision. It is shown on a geometrical model of nervous interaction that the appearance of Mach bands for certain patterns of stimulus distribution is correlated with nervous inhibition surrounding the area of sensation. This corroborates the earlier finding that surrounding every area transmitting sensation there is an area simultaneously transmitting inhibition.

Acoustic Stimulation↗
PubMed1993

Medullary afferent vagal axotomy disrupts NaCl-induced short-term taste aversion learning.

The effect of medullary afferent vagal axotomy on NaCl-induced short-term and long-term taste aversion learning (TAL) was examined to assess the relevance of the vagus nerve in drug-induced TAL. The results show that medullary afferent vagal axotomy disrupts NaCl-induced short-term (nondelayed) TAL, while having no effect on learning acquired with the same product in long-term (delayed) TAL protocols. Acquisition of learning in delayed discrimination tasks may be mediated by alternative mechanisms of nonvagal nature, e.g., the humoral system. The possibility that short-term and long-term TAL may be mediated by different neurobiological substrates is discussed.

Animals↗
PubMed1999

IP(3)-Independent release of Ca(2+) from intracellular stores: A novel mechanism for transduction of bitter stimuli.

A variety of substances with different chemical structures elicits a bitter taste. Several different transduction mechanisms underlie detection of bitter tastants; however, these have been described in detail for only a few compounds. In addition, most studies have focused on mammalian taste cells, of which only a small subset is responsive to any particular bitter compound. In contrast, approximately 80% of the taste cells in the mudpuppy, Necturus maculosus, are bitter-responsive. In this study, we used Ca(2+) imaging and giga-seal whole cell recording to compare the transduction of dextromethorphan (DEX), a bitter antitussive, with transduction of the well-studied bitter compound denatonium. Bath perfusion of DEX (2.5 mM) increased the intracellular Ca(2+) level in most taste cells. The DEX-induced Ca(2+) increase was inhibited by thapsigargin, an inhibitor of Ca(2+) transport into intracellular stores, but not by U73122, an inhibitor of phospholipase C, or by ryanodine, an inhibitor of ryanodine-sensitive Ca(2+) stores. Increasing intracellular cAMP levels with a cell-permeant cAMP analogue and a phosphodiesterase inhibitor enhanced the DEX-induced Ca(2+) increase, which was inhibited partially by H89, a protein kinase A inhibitor. Electrophysiological measurements showed that DEX depolarized the membrane potential and inhibited voltage-gated Na(+) and K(+) currents in the presence of GDP-beta-S, a blocker of G-protein activation. DEX also inhibited voltage-gated Ca(2+) channels. We suggest that DEX, like quinine, depolarizes taste cells by block of voltage-gated K channels, which are localized to the apical membrane in mudpuppy. In addition, DEX causes release of Ca(2+) from intracellular stores by a phospholipase C-independent mechanism. We speculate that the membrane-permeant DEX may enter taste cells and interact directly with Ca(2+) stores. Comparing transduction of DEX with that of denatonium, both compounds release Ca(2+) from intracellular stores. However, denatonium requires activation of phospholipase C, and the mechanism results in a hyperpolarization rather than a depolarization of the membrane potential. These data support the hypothesis that single taste receptor cells can use multiple mechanisms for transducing the same bitter compound.

1-Methyl-3-isobutylxanthine↗
PubMed2006

A 3 T event-related functional magnetic resonance imaging (fMRI) study of primary and secondary gustatory cortex localization using natural tastants.

INTRODUCTION: It is known that taste is centrally represented in the insula, frontal and parietal operculum, as well as in the orbitofrontal cortex (secondary gustatory cortex). In functional MRI (fMRI) experiments activation in the insula has been confirmed, but activation in the orbitofrontal cortex is only infrequently found, especially at higher field strengths (3 T). Due to large susceptibility artefacts, the orbitofrontal cortex is a difficult region to examine with fMRI. Our aim was to localize taste in the human cortex at 3 T, specifically in the orbitofrontal cortex as well as in the primary gustatory cortex. METHODS: Event-related fMRI was performed at 3 T in seven healthy volunteers. Taste stimuli consisted of lemon juice and chocolate. To visualize activation in the orbitofrontal cortex a dedicated 3D SENSE EPI fMRI sequence was used, in addition to a 2D SENSE EPI fMRI sequence for imaging the entire brain. Data were analyzed using a perception-based model. RESULTS: The dedicated 3D SENSE EPI sequence successfully reduced susceptibility artefacts in the orbitofrontal area. Significant taste-related activation was found in the orbitofrontal and insular cortices. CONCLUSION: fMRI of the orbitofrontal cortex is feasible at 3 T, using a dedicated sequence. Our results corroborate findings from previous studies.

Adult↗
PubMed2001

Determination of taste-active compounds of a bitter Camembert cheese by omission tests.

The taste-active compounds of a Camembert cheese selected for its intense bitterness defect were investigated. The water-soluble fraction (WSE) was extracted with pure water and fractionated by successive tangential ultrafiltrations and nanofiltration. The physicochemical assessment of these fractions led to the construction of a model WSE which was compared by sensory evaluation to the crude water-soluble extract, using a panel of 16 trained tasters. As no significant difference was perceived, this model WSE was then used directly or mixed with other cheese components for omission tests. Among the main taste characteristics of the WSE (salty, sour, umami and bitter), bitterness was found to be due to small peptides whose mass distribution was obtained by RPHPLC-MS (400-3000 Da) and whose taste properties are discussed.

Amino Acids↗
PubMed1999

Burning mouth syndrome: prevalence and associated factors.

Burning mouth syndrome (BMS) is characterized by a burning sensation in the oral cavity although the oral mucosa is clinically normal. The syndrome mostly affects middle-aged women. Various local, systemic and psychological factors have been found to be associated with BMS, but its etiology is not fully understood. Oral complaints and salivary flow were surveyed in 669 men and 758 women randomly selected from 48,500 individuals between the ages 20 and 69 years. Fifty-three individuals (3.7%), 11 men (1.6%) and 42 women (5.5%), were classified as having BMS. In men, no BMS was found before the age group 40 to 49 years where the prevalence was 0.7%, which increased to 3.6% in the oldest age group. In women, no BMS was found in the youngest age group, but in the age group 30 to 39 years the prevalence was 0.6% and increased to 12.2% in the oldest age group. Subjective oral dryness, age, medication, taste disturbances, intake of L-thyroxines, illness, stimulated salivary flow rate, depression and anxiety were factors associated with BMS. In individuals with BMS, the most prevalent site with burning sensations was the tongue (67.9%). The intensity of the burning sensation was estimated to be 4.6 on a visual analogue scale. There were no increased levels of depression, anxiety or stress among individuals with more pain compared to those with less pain. It was concluded that BMS should be seen as a marker of illness and/or distress, and the complex etiology of BMS demands specialist treatment.

Adult↗
PubMed2006

Taste perception and coding in the periphery.

Recent identification of taste receptors and their downstream signaling molecules, expressed in taste receptor cells, led to the understanding of taste coding in the periphery. Ion channels appear to mediate detection of salty and sour taste. The sensations of sweet, umami and bitter taste are initiated by the interaction of sapid molecules with the G-protein-coupled receptors T1Rs and T2Rs. Mice lacking either PLCbeta2 or TRPM5 diminish behavioral and nerve responses to sweet, umami and bitter taste stimuli, suggesting that both receptor families converge on a common signaling pathway in the taste receptor cells. Nevertheless, separate populations of taste cells appear to be uniquely tuned to sweet, umami and bitter taste. Since PLCbeta2-deficient mice still respond to sour and salty stimuli, sour and salty taste are perceived independent of bitter, umami and sweet taste. In this review, the recent characterization of the cellular mechanisms underlying taste reception and perception, and of taste coding in the periphery will be discussed.

Action Potentials↗
PubMed1995

Regulation of nutrient intake in humans: a theory based on taste and smell.

Oral and pharyngeal recognition of the chemical structure of physiologically relevant nutrients is proposed as a mechanism for regulating nutrient intake. Taste buds and olfactory receptors are proposed as the primary sites of recognition. Oral and pharyngeal sensory signals may be sufficient for producing satiation and termination of a meal provided the initiation of the meal is triggered by the body's need to replenish a deficient nutrient. A discussion of the impact of disturbances of normal regulation and some questions this model generates are also incorporated.

Eating↗
PubMed1984

Intragastric self-infusion of ethanol by ethanol-preferring and -nonpreferring lines of rats.

An ethanol-preferring line of rats, developed by selective breeding, consumed as much as 9.4 +/- 1.7 grams of ethanol per kilogram of body weight per day through intragastric self-infusions, yielding blood ethanol concentrations of 92 to 415 milligrams per 100 milliliters. By contrast, the ethanol- nonpreferring line self-administered only 0.7 +/- 0.2 gram per kilogram per day. These findings indicate that the reinforcing effect of ethanol is postabsorptive and is not mediated by the drug's smell or taste. Hence the ethanol-preferring line of rats may be suitable animal model of alcoholism.

Alcohol Drinking↗
PubMed2002

Factors in the school cafeteria influencing food choices by high school students.

This study set three objectives: 1) to examine the perceived influence of health concerns, labeling and nutrition information, taste, cost, availability, and peers on adolescents' food choices, particularly in the school cafeteria; 2) to determine whether these factors vary by gender, grade level, or adolescents' health and weight concerns; and 3) to provide recommendations regarding promotion of low-fat foods in the school cafeteria based on factors associated with food choices. Data were collected from a school survey that assessed key influences on adolescents' food choices, including low-fat foods. Some 289 students in grades 10-12 from a senior high school in a metropolitan area served as subjects. Descriptive statistics, chi-square, and general linear models were used for analysis. Results indicated that, when choosing foods from the school cafeteria, taste and getting a lot for their money were important to most students (93.7% and 71.7%, respectively). Females, and students who thought about their health and weight more frequently when deciding what to eat, were more likely to report greater interest in labeling and nutrition information and availability of low-fat foods in the school cafeteria. Findings suggest that efforts to promote low-fat foods to adolescents need to address the taste of low-fat foods, availability of low-fat options, and point-of-purchase labeling of low-fat foods. Focusing on the value and cost of low-fat foods may offer a key strategy for promoting low-fat foods to males.

Adolescent↗
PubMed1994

Associations of social and demographic variables with calcium intakes of high school students.

OBJECTIVE: To assess usual calcium intake of urban high school students and to assess the association of social and demographic variables with calcium intake. DESIGN: A self-administered survey instrument containing the following elements: a food frequency questionnaire (FFQ) developed to estimate calcium intake; questions to elicit demographic information; and scales to reflect taste enjoyment of dairy products, social reinforcement for consumption of milk, perceptions of others' opinions about milk, and behavioral modeling of milk consumption (ie, the frequency of observing friends' and family members' use of milk). The FFQ was shown to include major sources of calcium in diets of a pretest sample (n = 130). SETTING: Urban high schools in a metropolitan setting. SUBJECTS/SAMPLES: Students in one class per grade level in six high schools (approximately 900 students) were asked to participate. Of the 856 questionnaires completed, 785 were usable. MAIN OUTCOME MEASURES: Total calcium intake, as estimated using the FFQ. STATISTICAL ANALYSES PERFORMED: Descriptive statistics, t tests, one-way analysis of variance, correlation analysis, and stepwise multiple regression analysis were used to assess relationships of independent variables with calcium intake. RESULTS: Mean estimated calcium intakes for male and female students were 1,146 +/- 41 mg/day (mean +/- standard error of the mean) and 815 +/- 26 mg/day (P < .001), respectively, 59% of which was obtained from milk. Median intakes were 1,016 mg/day for boys and 676 mg/day for girls, and more than half the students had intakes that were below current recommendations. Multiple regression analysis revealed significant predictors of total calcium intake: gender (boys > girls); taste enjoyment of dairy products; number of meals and snacks per day; age; ethnicity (whites > Asians); behavioral modeling of milk consumption; perceptions of others' opinions, recommendations, and use of milk; and soft drink consumption (total adjusted R2 = .304). With the exception of age, these variables were positively associated with calcium intake. Regression equations developed for boys and girls separately revealed that different variables entered the equations. APPLICATIONS/CONCLUSIONS: Most of the variability in adolescents calcium intakes remained unexplained by the variables included in this study. Nevertheless, the results suggest that education programs focusing on taste enjoyment of dairy products and building on the influence of peers and family members may have a positive impact on calcium intake.

Adolescent↗
PubMed1994

Classification of taste responses in brain stem: membership in fuzzy sets.

1. Classification methods in sensory systems in general, and gustation in particular, tend to place each of the relevant objects, such as stimuli or neurons, into one class each. Some of these methods are based on the responsiveness of neurons to various stimuli; in these, each group must contain a variety of nonidentical members because of the individuality of each neuron or stimulus. 2. The "fuzzy" set method is appropriate for more accurate classification in such heterogeneous populations. In this method each member is given graded membership in several sets rather than membership in only one set. In the present paper we subjected previously published data on the responses of individual taste neurons to a variety of stimuli to fuzzy set analysis. 3. We found that the amounts of response of 46 neurons in the solitary nucleus of the rat to NaCl, HCl, sucrose, quinine HCl, and KCl could accurately be accounted for by giving each a grade of membership in three sets; the same held in the parabrachial nucleus of the rat for the responses of 41 neurons to the first four of these stimuli. The response was calculated as the sum of the products of the stimulus times neuron ratings in each set. 4. Temporal patterns of response have often been related, but with only moderate success, to the identity of the stimulus or neuron. These patterns could be accurately accounted for with the present method. Each of the products of designated parts of the stimulus ratings times the neuron ratings gave the basis for accurate description of the temporal course of the response of each neuron to each stimulus. 5. This method appears to account for the varieties of amount and temporal pattern of response of taste neurons with a simple mathematical process of few parameters. This suggests that within the known complexities of receptor mechanisms and mechanisms of neural processing, the neural message is reduced to a rather simple form. 6. The fuzzy set approach, which is based on disclosing underlying sets rather than placement of heterogeneous members into one of several essentialistic groups, may be useful in disclosure of the underlying mechanisms producing the neural responses in taste.

Animals↗
PubMed1990

Large synergism between monosodium glutamate and 5'-nucleotides in canine taste nerve responses.

The taste responses to the "umami" substances such as monosodium glutamate (MSG), GMP, and IMP were recorded from the chorda tympani nerve of mongrel dogs and beagles. A large synergism was observed between MSG and two species of nucleotides (GMP and IMP) in most mongrel dogs and between MSG and three species of nucleotides (GMP, IMP, and AMP) in beagles. The extent of the synergism between MSG and the nucleotides was much larger than that observed in any other animals examined except for humans. In the presence of GMP, the response magnitude of the chorda tympani nerve to MSG was increased but that to NaCl, HCl, sucrose, quinine, and glycine was unchanged. It was concluded that the canine taste responses to the umami substances closely resemble those in humans, and the dog is a suitable animal model for studies on the responses to the umami substances.

Animals↗
PubMed2005

Participant characteristics predicting voluntary early withdrawal from a multidisciplinary program providing home-delivered meals and dietitian/social work case management to homebound elders.

We examine whether baseline characteristics of participants enrolled in a multidisciplinary program providing home-delivered meals and dietitian/social work case management to homebound seniors predicted voluntary early withdrawal. Sixty-nine participants voluntarily withdrew early and 111 completed the project. Six hypotheses were based on a conceptual framework incorporating (1) agreement between project elements and needs/preferences of individuals and (2) whether participants would improve and no longer require or desire the intervention. Three of the hypotheses were supported by means of logistic regression analysis. Voluntary early withdrawers at baseline: (1) were more mobile, (2) ate less often, and (3) responded that food tastes good less often. The results suggest that carefully considering the interaction of potential participant characteristics and project interventions will improve nutrition project retention.

Activities of Daily Living↗
PubMed1981

The effect of post-conditioning exposure to morphine on the retention of a morphine-induced conditioned taste aversion.

In the following experiment, multiple injections of morphine sulfate following the acquisition of a morphine-induced taste aversion had no effect on the retention of the previously acquired aversion. Post-conditioning injections of morphine resulted in the development of physical dependence to morphine and led to a decrement in the ability of morphine to induce a subsequent aversion to a second novel taste. This failure of post-conditioning exposures to morphine to affect a previously acquired morphine-induced taste aversion even though tolerance to morphine had occurred was discussed in the context of Rescorla's event-memory model of conditioning.

Animals↗