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PubMed1987

The taste system encodes stimulus toxicity.

Attempts to define the organization of the taste system in terms of the physical characteristics of stimuli have been largely unsuccessful. We recorded taste-evoked neural activity in the rat's hindbrain and determined that stimuli could be effectively organized along a physiological dimension which corresponds to stimulus toxicity. Taste is a visceral sense that mediates between the external and internal chemical environments. Its responsiveness to a wide range of chemicals and its organization along a dimension which promotes the organism's physiological welfare ideally suit it to that purpose.

Action Potentials↗
PubMed2000

Resistance to extinction of conditioned odor perceptions: evaluative conditioning is not unique.

A tasteless odor will smell sweeter after being sampled by mouth with sucrose and will smell sourer after being sampled with citric acid. This tasty-smell effect was found in experiments that compared odor-taste and color-taste pairings. Using odors and colors with minimal taste (Experiment 1), the authors found that repeated experience of odor-taste mixtures produced conditioned changes in odor qualities that were unaffected by intermixed color-taste trials (Experiment 2). An extinction procedure, consisting of postconditioning presentations of the odor in water, had no detectable effect on the changed perception of an odor (Experiments 3 and 4). In contrast, this procedure altered judgments about the expected taste of colored solutions. Evaluative conditioning (conditioned changes in liking) is claimed to be resistant to extinction. However, these results suggest that resistance to extinction in odors is related to the way they are encoded rather than to their hedonic properties.

Adult↗
PubMed1990

Gustatory impairment and salivary gland pathophysiology in relation to oral cancer treatment.

Gustation and salivation were evaluated in 41 patients with oral carcinoma who were treated preoperatively with Peplomycin (PLM) or PLM + 5-FU + 60CO- radiation. Thresholds for sweet, salt, sour and bitter were originally elevated in many patients. Gustatory impairment increased especially with chemo- and radiotherapy. Recovery, however, took place within a year to almost original levels. Salivation was originally not impaired. Resting salivary flow rate (SFR) of the combined therapy group was decreased to half the initial rate, and a 20% decrease of SFR was seen in the PLM group. Corresponding to SFR, 99mTc uptake of the submandibular glands had declined, and salivary viscosity had increased. Salivary gland damage persisted during the study, and appeared irreversible. It was concluded from these results that taste impairment by oral cancer treatment is temporary, while damage to the salivary glands is permanent.

Adult↗
PubMed2000

[Reliability of electrogustatory threshold--electrogustometry using CNV].

CNV (contingent negative variation), an event-related potential, is induced when an oncoming imperative stimulus (S2) is anticipated after recognition of a warning stimulus (S1). With this in mind, we assessed the usefulness of electrogustometry using CNV as an objective gustatory test with an electric gustatory stimulus as a warning stimulus, S1. A gustatory test was performed on a total of 100 sides of the tongue in 50 subjects. Excluding no response cases on 5 sides in 5 subjects, the CNV threshold was successfully determined on 95 sides in 50 subjects. When the CNV threshold values obtained and the conventionally measured subjective threshold values were compared, a very high correlation was demonstrated between the two thresholds, with a correlation coefficient of 0.961. To assess the reliability of the CNV threshold, three additional measurements on 5 sides in 5 subjects with normal subjective threshold values were performed on different days, and the CNV threshold value variation among the three measurements in all 5 subjects never exceeded 13 microA. Separately, subjective threshold and CNV threshold values were compared in 4 patients with facial palsy (hence with gustatory abnormality) who consented to a follow-up examination. The difference between the subjective threshold and CNV threshold values in all 4 patients never exceeded 10 microA. These findings demonstrate that the reliability of the CNV threshold is satisfactory. Next, a gustatory imitation experiment was performed to assess the usefulness of electrogustometry using CNV as a means of detecting gustatory abnormality malingering. The experiment was performed on a total of 6 subjects: 3 physicians with knowledge of CNV (knowledge group) and 3 others with no knowledge of CNV (no-knowledge group). The differences between the imitated threshold and the subjective threshold values in all of these subjects never exceeded 10 microA, and the difference between imitated threshold and CNV threshold values never exceeded 13 microA. Comparison between the knowledge group and the no-knowledge groups showed that the imitated threshold values were very close to the subjective threshold and CNV threshold values. Based on the above results, it was concluded that gustometry using CNV is useful and can serve well as a method of objective evaluation of gustatory sensation. The results also suggested that it will be useful in diagnosing malingering.

Adolescent↗
PubMed2004

Gustatory responsiveness to monosodium glutamate and sodium chloride in four species of nonhuman primates.

The taste responsiveness of six squirrel monkeys, five pigtail macaques, four olive baboons and four spider monkeys to monsodium glutamate (MSG) and to sodium chloride was assessed in two-bottle preference tests of brief duration (2 min). When given the choice between tap water and defined concentrations of the two tastants dissolved in tap water, the animals were found to significantly discriminate concentrations of MSG as low as 2 mM (spider monkeys and olive baboons), 50 mM (pigtail macaques) and 300 mM (squirrel monkeys) from the solvent. With sodium chloride, taste preference thresholds were found to be 1 mM (spider monkeys), 20 mM (pigtail macaques), 50 mM (olive baboons), and 200 mM (squirrel monkeys), respectively. Across-species comparisons of the degree of preference for MSG and sodium chloride displayed by the four primate species showed the same order of spider monkeys>olive baboons>pigtail macaques>squirrel monkeys. When presented with equimolar concentrations of different tastants, all four species preferred sucrose as well as a mixture of sucrose and sodium chloride over MSG, and--at least at one concentration--they preferred MSG over sodium chloride. The results support the assertion that the taste responsiveness of the four primate species to MSG and sodium chloride might reflect an evolutionary adaptation to their respective dietary habits.

Animals↗
PubMed1987

Gustatory preference-aversion thresholds are increased by ibotenic acid lesion of the lateral hypothalamus in the rat.

The main purpose of this study was to quantitate possible changes in the rewarding and aversive values of certain gustatory stimuli produced by bilateral ibotenic acid lesions of the lateral hypothalamus in the rat. Non-operated rats served as controls. Thirteen days after the operation, rats were placed on a water-deprivation schedule during 5 consecutive days. Rats were then given the choice of one of 5 concentrations of saccharin solution, using a two-bottle procedure. Fluid intake across concentrations generated a preference-aversion curve. The same type of procedure was used to obtain the aversion curve for increasing concentrations of quinine solution. The lesioned rats as well as the control animals showed a clear preference-aversion response to saccharin solutions and an aversive response to quinine solutions. However, the highest preference score of the lesioned rats was obtained with a saccharin concentration 3 times higher than the concentration preferred by the control rats. Moreover, unlike control rats operated animals did not show aversion to the highest concentrations of saccharin solutions. Finally in the lesioned rats the aversion threshold to quinine solutions was obtained with concentration 5 times higher than the concentration inducing aversion in the control rats. At the end of these experiments, rats used as controls were submitted, in turn, to bilateral lesion of the lateral hypothalamus. The change in the preference-aversion threshold of these rats in the saccharin choice procedure was the same as that observed with naive rats. Taken together, these results suggest that in the normal rat the palatability of certain gustatory stimuli is modulated by the intrinsic neurons of the lateral hypothalamus.

Animals↗
PubMed1986

The effect of age on plasma zinc uptake and taste acuity.

Plasma uptake of a 25 mg oral dose of zinc was measured at 0, 1, 2, 3, and 4 h postdose in 16 elderly (mean age = 7.25 yr) and 12 young (mean age = 24.0 yr) subjects selected from a group of 62 healthy nonsmokers. Elderly and young subjects were divided into two groups based upon low or high detection thresholds for solutions of sodium chloride and sucrose. Mean fasting concentrations of plasma zinc were almost identical for the two age groups. Plasma response to a zinc dose was lower (p less than 0.05) in the elderly compared to that in the young, as indicated by plasma zinc levels at hours 2 and 3 postdose and by total area under the response curve. Moderate but significant age-associated increases in detection thresholds for both sodium chloride and sucrose were found; taste thresholds were not correlated to plasma uptake of the zinc dose in either age group.

Adolescent↗
PubMedDate not supplied

Does consumption of beer, alcohol, and bitter substances affect bitterness perception?

The relation between consumption of beer, alcohol, and bitter substances was investigated by comparing 20 each of male adults, low users ( < 720 ml/week) and high users ( > 3.61/week) of beer for sensitivity to and like/dislike for the bitterness of isohumulones. Intake of beer, alcohol, and bitter substances was measured with a food frequency questionnaire and a 14-day recall journal. Intake of alcohol (including alcohol from sources other than beer) and bitter substances was higher for high users of beer than for low users. The average bitterness units (BUs) in the beers consumed by the two groups did not differ, indicating that high users do not consume more bitter beers than low users. Detection thresholds for isohumulones in water did not differ between the two groups, but high users had higher difference thresholds for isohumulones in beer (p < 0.10). In time-intensity measurements of bitterness in beer, low users of beer recorded significantly higher maximum intensities (p < 0.001) and shorter total durations (p < 0.001) than high users, with no difference between the two groups for time to maximum intensity and area under the TI curve. There was no significant difference between the two groups for BUs of beers produced by ad lib mixing of low- and high-bitterness beers, or for mean hedonic ratings of various concentrations of isohumulones in beer. These results suggest that intakes of beer, alcohol, and bitter substances are not major determinants of taste responses to the bitterness of isohumulones.

Adult↗
PubMed2002

Taste and olfactory disturbances after upper and middle third facial fractures: a preliminary study.

To estimate smell and taste after traumatic disturbances, the authors questioned a sample of 92 patients who underwent surgical treatment for upper third and/or middle third facial fractures between January 1, 1988, and May 31, 1996, at the Department of Maxillofacial Surgery, University of Rome "La Sapienza," Italy. A total of 86 patients included in the study had a facial fracture sustained during a motor vehicle accident. Twenty-nine patients reported smell and/or taste after the traumatic disturbance. Of these 29 patients, 8 patients had hyposmia and/or anosmia without taste deficit, 10 patients had taste disturbances without smell loss, and 11 patients noted disturbance in both smell and taste. The authors encountered posttraumatic smell disturbances in 19 patients in their sample. Nasozygomatic-Le Fort fractures, fronto-orbital fractures, and pure Le Fort fractures were found to determine posttraumatic smell disturbances in these 19 patients. Nasal fractures, nasoorbital-ethmoidal fractures, ethmoidal fractures, frontal-Le Fort fractures, and nasal-Le Fort fractures did not determine any olfactory dysfunction. Posttraumatic hypogeusia and ageusia were found in 21 patients and was caused by nasozygomatic-Le Fort fractures, fronto-orbital fractures, and pure Le Fort fractures. The authors did not find any taste deficits after patients sustained other kinds of facial fractures. In the 11 patients observed, disturbances in both smell and taste were noted. Nasozygomatic-Le Fort fracture was the most common in these 11 patients. At 5 years' of follow-up, the results indicate that hypogeusia and hyposmia are connected with the etiology of fracture, the violence of the trauma, and the involvement of specific facial bone regions.

Accidents, Traffic↗
PubMed1991

[Bradley-Terry-Luce scale of taste qualities of champagne].

In a paired comparison experiment 783 subjects judged five different brands of champagne (three normal and two alcohol-reduced). Each subject judged only one single pair with respect to which one tasted more fizzy ("spritziger"), dry ("trockener"), prickling ("prickelnder") and better ("besser"). Three extended versions of the Bradley-Terry-Luce model are discussed and used to assess scale values for the criteria as well as for order effects. The results can be summarized into three points: (1) Goodness-of-fit for the simple BTL-model is satisfactory for all criteria--except for the judgement "tastes better than". (2) Using four graded response categories instead of dichotomous responses decreases goodness-of-fit considerably. (3) Alcohol-reduced brands are less "dry", but are quite within the range of the other brands with respect to the remaining criteria. It is argued that the particular scaling method used is especially useful for deciding which criteria are appropriate for measurement on a one-dimensional scale and which are not.

Carbonated Beverages↗
PubMed1981

Age and diabetes effects on threshold and hedonic perception of sucrose solutions.

This study explored the relationship of age and diabetes to the threshold and perception of the hedonic qualities of sucrose solutions. A significant increase in threshold beginning in the eighth decade was observed. Diabetic persons did not differ significantly in the threshold for sucrose from nondiabetic subjects. Younger individuals tended to judge suprathreshold solutions as sweeter than older persons. Results from pleasantness ratings were less clear but could be taken to imply that the younger, more recently diagnosed diabetic would find it more difficult to stay on a restricted diet necessary for the control of diabetes than would the older diabetic.

Adult↗
PubMed1985

Gustatory effectiveness of amino acids in mice: behavioral and neurophysiological studies.

Neural responses to L- and D-amino acids were recorded from the chorda tympani in the ddy mouse and their preferences were measured using the two-bottle choice technique. Most of the D- and L-amino acids elicited neural responses above 10-30 mM, but amino acids with basic side chains and their HCl derivatives produced responses at much lower concentrations. Among 19 amino acids examined, 3 D- and 7 L-amino acids were preferred, 5 L-amino acids were avoided and 4 were neutral to mice. The behavioral threshold to initiate either preference or aversion was negatively correlated with the hedonic intensity produced in mice, but not with the neural response threshold. The preference magnitude for L-amino acids at 0.1 M was negatively correlated with both MW and hydrophobicity of side chains. A high positive correlation was noted between preference magnitude in mice and hedonic intensity in humans. The role of molecular properties of amino acids in eliciting sweetness and bitterness is discussed.

Amino Acids↗
PubMed1988

Electrogustometry of the soft palate as a topographic diagnostic method for facial paralysis.

Electrogustometry (EGM) of the soft palate, innervated by the gustatory fibers running via the greater petrosal nerve, was performed in 10 cases with facial paralysis due to suprageniculate lesions to evaluate its clinical validity as a topographic diagnostic method. Lacrimal function was also examined for comparison. The results obtained from EGM showed a significantly increased threshold on the affected side in 90% of the cases. However, the lacrimal secretion decreased only in 40% using Schirmer No. 2 test. The results of the present study strongly suggest that EGM of the soft palate reflects the function of this nerve better than Schirmer test, and EGM is clinically useful for the topographic diagnosis of peripheral facial nerve lesions.

Adult↗
PubMed1988

Minerals and vitamin-A status in relation to gustatory functions for salt in healthy female college students.

Twenty-five healthy female college students were studied for the gustatory function tests for salt (NaCl) and some selected biochemical parameters including plasma retinol and plasma retinol-binding protein (PRBP). Plasma zinc (PZn) and retinol levels were comparable with those of good responders in tests of discrimination between two levels of NaCl in the previous report, but PRBP was lower in the present subjects. From the results of correlation analysis and stepwise multiple regression analysis, the individual student's discriminability of NaCl concentrations was related to the parameters regarding metabolic status of calcium (Ca), magnesium (Mg), sodium (Na), and selenium (Se). The detection threshold of NaCl concentration ranged from 1 to 60 mmol/liter and was related to PRBP. Plasma Zn was significantly positively correlated with both plasma retinol and PRBP, but significantly negatively correlated only for the detection threshold of NaCl concentration. On the basis of these results, the importance of vitamin-A nutrition and the relation of minerals such as Na, Ca, Mg, and Zn to the gustatory functions of NaCl was confirmed and a possible participation of Se to the functions was suggested.

Adult↗
PubMed2002

Turbidity as a measure of salivary protein reactions with astringent substances.

Binding of tannins to proline-rich proteins has been proposed as an initial step in the development of astringent sensations. In beer and fruit juices, formation of tannin-protein complexes leads to the well-known effect of haze development or turbidity. Two experiments examined the development of turbidity in human saliva when mixed with tannins as a potential in vitro correlate of astringent sensations. In the first study, haze was measured in filtered human saliva mixed with a range of tannic acid concentrations known to produce supra-threshold psychophysical responses. The second study examined relationships among individual differences in haze development and the magnitude of astringency ratings. Mostly negative correlations were found, consistent with the notion that high levels of salivary proteins protect oral tissues from the drying effects of tannic acid.

Adolescent↗
PubMed1984

[Features of vascular reactivity, sodium metabolism and its humoral regulation in healthy subjects with a family history of hypertension].

The examination of 140 normal individuals with a family history of essential hypertension (FHEH) showed a number of differences in their cardiovascular and renin-aldosterone responses as compared to 170 normal subjects of the control group. Two years later the results were analyzed once again with regard to blood pressure changes. It turned out that subjects with a FHEH and an unfavourable pattern of blood pressure changes over two years exhibited elevated response of cutaneous vessels to angiotensin and noradrenaline, a higher threshold of gustatory sensitivity to salt and an increased BP response to psychoemotional stress already during the first examination. It is concluded that the most informative markers of the prehypertension state among the genetically determined features characteristic of healthy individuals with a FHEH are changes in sodium metabolism and regulation which are responsible for the development of vascular hyperactivity.

Adult↗
PubMed1996

[Predictive value of electrogustometry in the preoperative diagnosis of severity of middle ear pathology].

The chorda tympani nerve (CTN) is frequently damaged in various inflammatory middle ear disorders. To determine the validity of electrogustometry in the diagnosis of preoperative severity of a middle ear lesion of the posteosuperior portion of the mesotympanum, the threshold determined by electrogustometry was examined preoperatively and was correlated with the intraoperative findings. One hundred and six ears of 97 patients with various middle ear diseases were examined. The patients ranged in age from 5 to 70 years (average, 39.4) : 55 of them were male and 42 were female. In 80 of them the appearance of the tympanic membrane on the opposite side was normal. The disorders were classified as follows: A : Non-inflammatory diseases including middle ear anomalies, posttraumatic perforation of the tympanic membranes and congenital cholesteatoma without infection (n = 10) ; B : chronic otitis media without cholesteatoma (n = 14) ; C : pars flaccida retraction type cholesteatoma (n = 34) ; D : pars tensa retraction type cholesteatoma and adhesive otitis media (n = 15) ; E : surgically treated ears (n = 33). The average threshold +/- S.D.(dB) of each group according to the above classification was as follows : A : -1.0 +/- 4.4, B : -1.5 +/- 6.2; C : 7.4 +/- 13.7; D : 9.6 +/- 18.2; E : 20.9 +/- 16.8. The rates of abnormal threshold of electrogustometry (more than 8dB) of A, B, C, D and E were 0%, 7.1%, 44.1%, 46.7% and 72.7%, respectively. The intraoperative findings around the CTN were retrospectively classified according to the following 5 groups : I : No pathological tissue was attached to the CTN (n = 44); II : the Granulation tissue or matrix of the cholesteatoma was attached to the CTN (n = 19) ; III : the CTN was surrounded by granulation or a matrix of cholesteatoma (n = 3) ; IV : The CTN was not identifiable due to the severe pathological condition of the middle ear cavity, in either surgically treated or untreated ears (n = 16), V : Surgically treated ears in which the CTN was identifiable (n = 24). The average threshold +/- S.D.(dB) for I, II, III, IV and V were 1.9 +/- 9.6, 2.0 +/- 11.7, 16.0 +/- 20.3, 32.0 +/- 7.4, 16.0 +/- 17.0, respectively. The rates of abnormal threshold of electrogustometry (more than 8dB) of I, II, III, IV and V were 27.3%, 31.6%, 66.7%, 100% and 62.5%, respectively. In both the above classification by the disorders and that by the intraoperative findings around the CTN, differences in the average thresholds between the surgically treated sides and the opposite sides with normally appearing tympanic membranes showed a tendency similar to that of the thresholds of the treated sides. In the present study, the threshold of electrogustometry was correlated with the disease and the intraoperative findings during middle ear surgery, and it was higher in adhesive otitis media and cholesteatoma of the pars tensa type. Electrogustometry is a useful preoperative examination to predict the condition of the posterosuperior portion of the mesotympanum.

Adolescent↗
PubMedDate not supplied

Sodium detection threshold and preference for sodium chloride in humans on high and low sodium diets.

Sodium detection threshold and preference for sodium chloride was examined in human volunteers on 2 week periods of high and low salt diets. There was no significant difference in salivary electrolytes or sodium detection threshold between the high and low salt diet periods. Sodium preference, defined as the final sodium concentration of unsalted tomato juice following the ad libitum addition of NaCl, was significantly less on the low salt diet when compared to the high salt period. These results suggest that short periods of dietary salt modification can result in marked shifts in preference for NaCl in the absence of changes in the physiological parameters measured.

Adult↗