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At least 19 recordsLinked to original sources
PubMed1987

Qualitative differences in polysaccharide and sugar tastes in the rat: a two-carbohydrate taste model.

A conditioned taste aversion paradigm was used to assess the qualitative similarities between the tastes of a polysaccharide (Polycose) solution and sugar solutions (sucrose, maltose, glucose, fructose). In Experiment I, three groups of female rats were water deprived and conditioned to avoid a 0.025 M Polycose, a 0.1 M sucrose, or a 0.1 M maltose solution by pairing solution consumption with a lithium chloride (LiCl) injection; in a control group water consumption was paired with the LiCl injection. The extent to which the experimental groups generalized their conditioned aversion to the other three solutions was then assessed. The Polycose-conditioned group avoided the maltose solution more than the sucrose solution, and the maltose-conditioned group avoided the Polycose solution more than the sucrose solution. The sucrose-conditioned group avoided the maltose and Polycose solutions to the same relatively low degree. In additional tests the three experimental groups showed similar aversions to a glucose solution, but only the sucrose-conditioned rats avoided a fructose solution. Rats in a second experiment also displayed relatively little cross-generalization between Polycose and sucrose aversions even though they were tested with different solution concentrations. Additional tests confirmed the results obtained in Experiment 1 with maltose, glucose, and fructose solutions, and also revealed that the sucrose-conditioned group, but not the Polycose-conditioned group avoided saccharin solutions. Neither Polycose- nor sucrose-conditioned groups avoided quinine, sodium chloride, or hydrochloric acid solutions. These results, along with other recent findings, suggest that rats have two types of "carbohydrate" taste receptors, one for polysaccharides and one for sucrose, which produce qualitatively distinct gustatory sensations.

Animals↗
PubMed1990

Chemotransduction in Necturus taste buds, a model for taste processing.

The taste bud in Necturus serves as a good model for taste mechanisms in vertebrates. The large size of taste cells and relative accessibility of the tissue for detailed electrophysiological and ultrastructural studies makes this species well-suited for studying taste transduction. Important features of taste transduction that have been learned from investigations in Necturus are that voltage-gated potassium channels are preferentially distributed on the apical membrane of taste cells; voltage-gated potassium channels allow K ions to enter the cell when taste buds are stimulated with K salts; some chemical stimuli act by closing K channels, thereby eliciting depolarizing receptor potentials in taste cells. Many of these findings have been confirmed and extended in other animals, including mammals. Furthermore, recent evidence from experiments in Necturus suggests that there is a considerable degree of synaptic coupling among taste cells. This synaptic coupling could form the basis for signal processing and integration in the peripheral sensory organs of taste, the taste buds.

Animals↗
PubMed1977

Mixtures of substances with similar tastes. A test of a psychophysical model of taste mixture interactions.

When substances of similar taste are mixed, the mixture can show suppression or synergism. That is, the perceived intensity of the mixture can be less than or greater than the sum of the perceived intensities of the components. In the present study, these departures from simple additivity could be predicted from the psychophysical functions relating tast intensity to stimulus concentration of the unmixed components. Psychophysical functions are said to show compression when successive increments in concentration produce progessively smaller increments in perceived intensity and to show expansion when successive increments in concentration produce progressively larger increments in perceived intensity. Suppression resulted from mixtures of substances with compressed psychophysical functions, and synergism resulted from mixtures of substances with expanded functions.

Adult↗
PubMed1987

The equiratio taste mixture model successfully predicts the sensory response to the sweetness intensity of complex mixtures of sugars and sugar alcohols.

The equiratio taste mixture model was originally developed for the prediction of psychophysical power functions of equiratio mixtures of substances that have a similar taste and that also exhibit mutual cross adaptation. Earlier studies have shown that the model is valid for mixtures of sugars and/or sugar alcohols. Two experiments are reported in which it is questioned whether the psychophysical functions of mixtures of higher physical complexity can be predicted by the model. In the first experiment the psychophysical power functions of binary and quaternary equiratio mixture types were determined experimentally and compared to those predicted by the generalized model. In the second, similar, experiment quaternary and eight-component mixture types were examined. The method of magnitude estimation, in combination with the sip and spit procedure, was used. The functions predicted by the model were almost identical to the functions established on the basis of the experimental data. These results reconfirm that the gustatory modality operates like an 'averaging' system when processing this kind of mixture. It is argued that for other kind of mixtures the model will predict incorrectly. The status of the equiratio mixture model is discussed.

Adolescent↗
PubMed1983

Modification of the triangle-taste-test model to allow for nonforced guessing.

The modified triangle taste test proposed here allows for nonforced guessing. The maximum likelihood estimator (MLE) for the true proportion of distinguishers is derived. For the range of values examined, this estimator results in less bias and smaller variance than the MLE of the conventional (forced-guessing) model. For the modified (nonforced-guessing) model, an upper bound on the variance of the estimator is derived, along with an approximate 95% confidence interval for the proportion of distinguishers in the population.

Analysis of Variance↗
PubMed2004

Taste perception: Drosophila - a model of good taste.

Recent studies of taste receptors in Drosophila show remarkable parallels with the mammalian gustatory system, although the pathways are anatomically distinct. These parallels may reflect crucial constraints in the design of taste detection systems.

Animals↗
PubMed1994

Capability of intensity discrimination in multiple receptor model of insect taste.

A simple model in which one CNS taste neuron integrates inputs from multiple peripheral receptors is introduced in order to investigate the mechanism of acute intensity taste discrimination in flies. Information theory is applied to evaluate the acute ability of discrimination provided by the model. The present analysis is carried out under two statistical conditions concerning the uncertainty of receptor response. Based on experimental data obtained by Smith et al. (1983), we estimate the mutual information entropy of the model. The numerical results obtained here indicate that the uncertainty observed in a single receptor response is dramatically reduced by the central integration. Furthermore, each of the eleven stimulus intensity levels experimentally applied by Smith et al., can be discriminated completely by integrating the responses of the realistic number of receptors (33-212). Such a great improvement of the differential sensitivity in the model resolves the discrepancy between the low differential sensitivity of single sugar receptors (Smith et al., 1983) and the high sensitivity obtained in the feeding behavior (Dethier and Rhoades, 1954; Dethier and Bowdan, 1984) of the blowfly.

Animals↗
PubMed1990

A conceptual model of taste receptors.

Of all the senses, that of taste is perhaps the hardest to define and quantify and elucidation of the underlying mechanisms is unrespondingly difficult. This article describes a conceptual model--at the molecular level--for the four basic taste modalities, using apparent specific volume as a fundamental parameter. It also considers possible practical applications.

Humans↗
PubMed1990

A taste aversion model of drug discrimination learning: training drug and condition influence rate of learning, sensitivity and drug specificity.

A model of drug discrimination based on a lithium chloride (LiCl) flavour aversion was described and examined. Mildly thirsty rats were presented daily with 4 ml of a distinctly flavoured solution which was followed on 50% of the days by an IP injection of LiCl. Prior to the flavour presentation, the rats were injection SC with saline or a training drug (0.04 mg/kg fentanyl or 20 mg/kg pentobarbital) to signal whether LiCl would follow. Almost all rats eventually exhibited stable behaviour that involved drinking most or all of the fluid when it was not to be followed by LiCl and little or no drinking when it was. Such discrimination occurred regardless of whether drug predicted LiCl (learned-discomfort) or predicted no LiCl (learned-safety). However, with fentanyl there were clear differences between rats trained with drug under learned-safety and under learned-discomfort conditions for 1) the rate of acquisition of stable performance as a function of LiCl dose, 2) generalization of the training dose to a test dose that was lower, and 3) elicitation of fentanyl responses by pentobarbital. These findings, together with indications that such effects did not always occur with pentobarbital as the training drug, were discussed from theoretical and practical perspectives.

Animals↗
PubMed1988

Liposomes as model for taste cells: receptor sites for bitter substances including N-C=S substances and mechanism of membrane potential changes.

Various bitter substances were found to depolarize liposomes. The results obtained are as follows: (1) Changes in the membrane potential of azolectin liposomes in response to various bitter substances were monitored by measuring changes in the fluorescence intensity of 3,3'-dipropylthiocarbocyanine iodide [diS-C3(5)]. All the bitter substances examined increased the fluorescence intensity of the liposome-dye suspension, which indicates that the substances depolarize the liposomes. There existed a good correlation between the minimum concentrations of the bitter substances to depolarize the liposomes and the taste thresholds in humans. (2) The effects of changed lipid composition of liposomes on the responses to various bitter substances vary greatly among bitter substances, suggesting that the receptor sites for bitter substances are multiple. The responses to N-C=S substances and sucrose octaacetate especially greatly depended on the lipid composition; these compounds depolarized only liposomes having certain lipid composition, while no or hyperpolarizing responses to these compounds were observed in other liposomes examined. This suggested that the difference in "taster" and "nontaster" for these substances can be explained in terms of difference in the lipid composition of taste receptor membranes. (3) It was confirmed that the membrane potential of the planar lipid bilayer is changed in response to bitter substances. The membrane potential changes in the planar lipid bilayer as well as in liposomes in response to the bitter substances occurred under the condition that there is no ion gradient across the membranes. These results suggested that the membrane potential changes in response to bitter substances stem from the phase boundary potential changes induced by adsorption of the substances on the hydrophobic region of the membranes.

Benzothiazoles↗
PubMed1995

Pruning of rat cortical taste neurons by an artificial neural network model.

1. Taste qualities are believed to be coded in the activity of ensembles of taste neurons. However, it is not clear whether all neurons are equally responsible for coding. To clarify the point, the relative contribution of each taste neuron to coding needs to be assessed. 2. We constructed simple three-layer neural networks with input units representing cortical taste neurons of the rat. The networks were trained by the back-propagation learning algorithm to classify the neural response patterns to the basic taste stimuli (sucrose, HCl, quinine hydrochloride, and NaCl). The networks had four output units representing the basic taste qualities, the values of which provide a measure for similarity of test stimuli (salts, tartaric acid, and umami substances) to the basic taste stimuli. 3. Trained networks discriminated the response patterns to the test stimuli in a plausible manner in light of previous physiological and psychological experiments. Profiles of output values of the networks paralleled those of across-neuron correlations with respect to the highest or second-highest values in the profiles. 4. We evaluated relative contributions of input units to the taste discrimination of the network by examining their significance Sj, which is defined as the sum of the absolute values of the connection weights from the jth input unit to the hidden layer. When the input units with weaker connection weights (e.g., 15 of 39 input units) were "pruned" from the trained network, the ability of the network to discriminate the basic taste qualities as well as other test stimuli was not greatly affected. On the other hand, the taste discrimination of the network progressively deteriorated much more rapidly with pruning of input units with stronger connection weights. 5. These results suggest that cortical taste neurons differentially contribute to the coding of taste qualities. The pruning technique may enable the evaluation of a given taste neuron in terms of its relative contribution to the coding, with Sj providing a quantitative measure for such evaluation.

Animals↗
PubMed1984

Physical model approach to taste studies of drugs and pharmaceutical formulations.

This paper explores the physical model approach in studying the taste of drugs and assessing physical formulation factors for improving the undesirable taste of drugs. Various aspects of physiology relevant to the taste phenomenon have been reviewed to provide the biophysical basis for mathematical modeling. The model involves non-steady-state mass transport across the aqueous boundary layer and buildup of solute concentration at the essentially impermeable tongue surface. The theoretical predictions are consistent with experimental studies on the lag time to taste perception by the electrophysiological method and also with "instantaneous" psychophysical taste perception when solute concentrations much greater than the taste threshold are applied on the tongue. Within the framework of the non-steady-state model, novel experimental studies involving the use of a porous half-diffusion cell placed on the surface of an extended human tongue and the recording of the times for psychophysical taste response are proposed to quantify and provide mechanistic understanding of the taste of drugs and also physical formulation factors in overcoming undesirable taste properties.

Animals↗
PubMed1990

A comparison and latent variable test of two fertile ideas.

A test is constructed to distinguish between the Becker and the Easterlin models of the economics of fertility. Both suggest possible biases due to unobserved variables. It is demonstrated that "while the Becker endowment and Easterlin taste models can be expressed in terms of the same variables, it is possible to identify each of the models because of different signs in a latent variable system that uses information from individuals, siblings, and cousins. Estimates of this model are consistent with the Easterlin, but not the Becker formulation. But neither model results in significant income coefficient estimates." The geographical focus is on the United States.

Americas↗
PubMed2005

Molecular definition of black tea taste by means of quantitative studies, taste reconstitution, and omission experiments.

Recently, bioresponse-guided fractionation of black tea infusions indicated that neither the high molecular weight thearubigens nor the theaflavins, but a series of 14 flavon-3-ol glycopyranosides besides some catechins, might be important contributors to black tea taste. To further bridge the gap between pure structural chemistry and human taste perception, in the present investigation 51 putative taste compounds have been quantified in a black tea infusion, and their dose-over-threshold (Dot) factors have been calculated on the basis of a dose/threshold relationship. To confirm these quantitative results, an aqueous taste model was prepared by blending aqueous solutions of 15 amino acids, 14 flavonol-glycosides, 8 flavan-3-ols, 5 theaflavins, 5 organic acids, 3 sugars, and caffeine in their "natural" concentrations. Sensory analyses revealed that the taste profile of this artificial cocktail did not differ significantly from the taste profile of the authentic tea infusion. To further narrow the number of key taste compounds, finally, taste omission experiments have been performed, on the basis of which a reduced recombinate was prepared containing the bitter-tasting caffeine, nine velvety astringent flavonol-3-glycosides, and the puckering astringent catechin as well as the astringent and bitter epigallocatechin-3-gallate. The taste profile of this reduced recombinate differed not significantly from that of the complete taste recombinate, thus confirming these 12 compounds as the key taste compounds of the tea infusion. Additional sensory studies demonstrated for the first time that the flavanol-3-glycosides not only impart a velvety astringent taste sensation to the oral cavity but also contribute to the bitter taste of tea infusions by amplifying the bitterness of caffeine.

Amino Acids↗
PubMed1986

Structure-taste correlation of L-aspartyl dipeptides using SIMCA method.

One of the pattern recognition techniques, the SIMCA method, has been applied to structure-taste studies on L-aspartyl dipeptides (L-Asp-NH-R). The sweet and bitter taste class models of the peptides were obtained by using five structural descriptors, such as molar refractivity, and four kinds of STERIMOL parameters. The classification rates were calculated to be 87% and 81% for sweet and bitter peptides, respectively. The SIMCA method has also suggested that two factors, shape and size, of the C-terminal amino acid moiety R in the dipeptides are extremely important to model their taste qualities.

Aspartic Acid↗