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Results for “Taste Threshold”

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PubMed1990

[Taste disorders in chromium exposed workers].

Taste thresholds were investigated by means of chemical and electric stimulation in order to prove the induction of taste disturbances by chrome dust. There were examined 46 persons with exposition by potassium bichromate, chromic acid and zinc chromate, 19 of them working under conditions of a lower chrome exposition level but 27 of them working under conditions of a higher chrome exposition level. We could find a increasing threshold in taste qualities "sweet", "poor", "salty" and "bitter" corresponding to an increase of chrome exposition on the one hand and likewise of electric stimuli on the other hand. The quantity of chrome exposition must be regarded more important than its quality and its duration. Finally we want to recommend the appliance of always as electrogustometry as chemogustometry for occupational taste investigations because both the methods seem to differ somewhat.

Ageusia↗

PubMed2002

[Taste disorders].

PURPOSE: This review focuses on the present state of the question about taste disorders with reference to their associated factors, diagnostic methods, and potential effects. CURRENT KNOWLEDGE AND KEY POINTS: Taste disorders may be induced by many drugs and are associated to a number of acute or chronic diseases. Patients may be asked about their taste complaints, and taste thresholds may be determined by electrogustometry or chemical gustometry. Taste impairment may provide a good indicator to the course of some diseases such as diabetes mellitus in which hypogeusia predicts occurrence of degenerative complications. Dysgeusia may induce nutritional disorders and contribute to wasting in chronic liver disease, cancer, or human immunodeficiency virus infected patients. Mechanisms involved in dysgeusia are more than one in a patient. Taste disturbance may be secondary to a variety of causes that include zinc deficiency, lesions of the lingual epithelium, neurological impairment, and a pharmacological effect. FUTURE PROSPECTS AND PROJECTS: A better understanding of the transduction mechanisms of the gustatory signal and the main pathogenic factors involved in dysgeusia may possibly improve the follow-up of the concerned patients notably in terms of nutritional status.

Acute Disease↗

PubMed2004

Effects of stimulation duration on electrogustometric thresholds.

The ability to detect low electrical currents presented to the lingual surface is widely used to assess taste function in humans. Despite this fact, the influence of stimulus duration on electrical taste thresholds is not well established. In this study, we evaluated the effects of current duration (0.5, 1.0, and 1.5 s) on electrogustometric detection thresholds for two regions of the anterior tongue in 24 college students. Anodal stimulation was produced using a stainless steel 12.5-mm(2) electrode, and thresholds were determined using a single-staircase procedure. A non-monotonic function for the threshold values was observed for both tongue regions across the stimulus durations, with the 1.0-s duration stimulus resulting in a lower threshold value (i.e., higher sensitivity) than either the 0.5- or 1.5-s durations, which did not differ in magnitude from one another. These data suggest that stimulus-duration-related enhancement of lingual detection threshold sensitivity to electric currents disappears at some point after 1 s.

Adolescent↗

PubMed1979

Taste acuity of the human palate. III. Studies with taste solutions on subjects in different age groups.

The taste acuity at the midline of the hard and soft palate near their junction and, for comparison, on representative areas of the tongue was determined in 80 subjects aged 11-79 years by applying test solutions of the four basic tastes. Twenty-one subjects (26%) could identify at least one taste on the hard palate but none could recognize all four tastes. Seventy subjects (87%) could identify at least one taste on the soft palate and 37 subjects (46%) could recognize all four tastes. Taste thresholds were much higher on the hard palate than on the tongue and were in most cases higher on the soft palate than on the tongue. The ability to recognize all four tastes was less frequent in older than in younger subjects and the difference was greatest on the soft palate and least at the foliate papillae. The differences were greatest for citric acid and least for sucrose. There was a tendency to lower thresholds for women compared to men for all four tastes on all areas examined which was most pronounced on the soft palate. No differences in taste thresholds were found between denture wearers and subjects with natural dentition. Smokers had higher thresholds than non-smokers only for salt on the soft palate and the base of the tongue.

Adolescent↗

PubMed2001

Fast and accurate measurement of taste and smell thresholds using a maximum-likelihood adaptive staircase procedure.

This paper evaluates the use of a maximum-likelihood adaptive staircase psychophysical procedure (ML-PEST), originally developed in vision and audition, for measuring detection thresholds in gustation and olfaction. The basis for the psychophysical measurement of thresholds with the ML-PEST procedure is developed. Then, two experiments and four simulations are reported. In the first experiment, ML-PEST was compared with the Wetherill and Levitt up-down staircase method and with the Cain ascending method of limits in the measurement of butyl alcohol thresholds. The four Monte Carlo simulations compared the three psychophysical procedures. In the second experiment, the test-retest reliability of MLPEST for measuring NaCl and butyl alcohol thresholds was assessed. The results indicate that the ML-PEST method gives reliable and precise threshold measurements. Its ability to detect malingerers shows considerable promise. It is recommended for use in clinical testing.

Adolescent↗

PubMed2006

Chorda tympani nerve transection alters linoleic acid taste discrimination by male and female rats.

Taste is intimately associated with food choice, yet little is known about the role of taste in preferences for dietary fat, a major component of many foods. We measured the taste threshold for linoleic acid (LA), an essential free fatty acid found in dietary fat, before and after bilateral transections of the chorda tympani nerve (CTX) in adult male and female rats. We conditioned a taste aversion to 88 microM LA and assessed the generalization of the aversion to lower LA concentrations to determine LA discrimination thresholds. We discovered that female rats had a lower LA discrimination threshold (approximately 2.75 microM LA) than did male rats (approximately 11 microM LA). In another set of animals, we performed CTX and found that CTX elevated LA threshold to the same level (approximately 22 microM LA) in male and female rats. Finally, we evaluated licking responses to 11, 22, 44 and 88 microM LA mixed in sucrose by male rats and ovariectomized (OVX) female rats treated with estradiol benzoate or oil vehicle. All rats increased licking to increasing LA concentrations, but OVX rats responded to a lower LA concentration (22 microM) than did males (44 microM) in 10-s trials. However, estradiol did not affect this outcome. Collectively, these experiments show that male and female rats use taste to discriminate LA and that the chorda tympani nerve, which innervates taste buds on the anterior tongue, plays a role in this discrimination. Furthermore, sex differences in fat preferences may depend on differences in fatty acid taste thresholds as well as on the taste stimuli with which fat is combined.

Analysis of Variance↗

PubMed1995

Selective inhibition of bitter taste of various drugs by lipoprotein.

Previously, we demonstrated that lipoprotein composed of phosphatidic acid (PA) and beta-lactoglobulin (LG) selectively and reversibly suppress the frog taste nerve response to bitter substances. In the present study, we examined the effects of various lipoproteins on the taste sensation to various stimuli in humans by a psychophysical method. Among various lipoproteins composed of different of lipids and proteins, the lipoproteins composed of PA and proteins were most effective in suppressing bitter taste. The lipoproteins composed of PA and LG, bovine serum albumin, ovalbumin, alpha-lactoalbumin or casein similarly suppressed effects on sensation of bitter taste. Using PA-LG, the effects on taste sensation to various stimuli were examined. The bitter taste of all twelve substances examined was inhibited, while saltiness of NaCl and sweetness of sucrose were not inhibited. The inhibition of bitter taste was completely reversible. Masking of the target sites for bitter substances on the taste receptor membranes with PA-LG seems to contribute to the inhibition of bitter taste. Direct binding of the bitter substances to PA-LG in the medium also contributes to the inhibition of bitter taste of certain substances. Among various drugs, basic and hydrophobic substances such as quinine, denatortium and propranolol have low taste thresholds and are said to be the most bitter. PA-LG most effectively suppressed the bitter taste of such substances. PA originates from soybeans and the proteins used except for bovine serum albumin originate from milk or eggs, and hence the lipoproteins can be safely used to mask the bitter taste of drugs.

Caffeine↗

PubMed1998

[Quantitative studies of taste and fungiform papillae on the anterior human tongue].

OBJECTIVE: To study qantitatively in the taste and fungiform papillae on the anterior human tongue. METHODS: Sixty normal adults were evaluated the spatial taste and the fungiform papilla density at spatially-matched sides on the right and left sides of the anterior tongue. The taste stimulative solutions were delivered to a spatially-matched flow chamber attached to the surface of the right or left anterior tongue. RESULTS: (1) There is no statistical difference in number of the fungiform papillae, taste threshold and magnitude matching between right/left, male/female and races; (2) There is a significant difference in fungiform papilla density and taste functions in different individuals; (3) The fungiform papilla density is the key to taste function on 2/3 anterior of tongue, and is positively correlated to it; (4) The use of a spatially-matched flow chamber is a valid test system for overall, objective and accurate evaluating taste on the 2/3 anterior of tongue, and can be used to study quantitatively the fungiform papilla density. CONCLUSION: It is of clinical significance for the diagnosis of taste diseases and the dynamic studies of the taste and the fungiform papillae after lingual nerve injury and repair.

Adolescent↗

PubMed1987

Salivary changes in solution pH: a source of individual differences in sour taste perception.

The role of saliva in sour taste perception was investigated in a series of 4 experiments. In one pair of experiments, solution pH was measured before and after acetic, citric or hydrochloric acid solutions were mixed with saliva either normally in the oral cavity or after saliva was directly added to solutions. The results showed that large increases in solution pH occurred over a wide range of acid concentrations and that the changes in pH were related to individual salivary flow rates; greater increases in solution pH occurred among those individuals with higher flow rates. The other pair of experiments measured taste threshold and suprathreshold responses to different volumes of acids. The results demonstrated that individuals with high salivary flow rates were less sensitive to the taste of acids and that large volumes of acid were more easily perceived. The pattern of findings suggest that saliva-induced changes in solution pH are important in sour taste perception.

Adolescent↗

PubMed1977

Enzymatic oxydation of linoleic acid: formation of bittertasting fatty acids.

Linoleic acid was oxidized with a protein fraction from soya beans (25 degrees C; 2h), in which lipoxygenase and peroxydase activities occurred. The fatty acids formed were isolated and, after emulsification with a sugar ester, were evaluated for bitter taste. The main components of the bitter-tasting fractions was a mixture of 9.12.13-trihydroxyoctadec-10- and 9.10.13-trihydroxyoctadec-11-enoic acids. The taste threshold lies in the range 0.6-0.9 mumol/ml. Two further trihydroxy-acids and two oxodihydroxy-acids were also identified in the bitter-tasting fraction.

Fatty Acids↗

PubMed2002

The effect of microgravity and space flight on the chemical senses.

The effect of space flight and microgravity on the chemical senses is reviewed. Skylab-4 and Soyuz 30-31 studies revealed changes in taste thresholds while no effect was found in a Canadian investigation (41-G) and conflicting results were obtained on another Soyuz mission. Two simulated microgravity studies found no effect on taste or smell sensitivity; while 5 other studies found an effect. Microgravity induces physiological changes including an upward shift of body fluids toward the head, which may lead to an attenuation of the olfactory component in the flavor of foods. Chemosensory changes may also relate to space sickness, Shuttle atmosphere, stress, radiation, and psychological factors.

Adult↗

PubMedDate not supplied

Association of phenylthiocarbamide taste sensitivity with diabetes mellitus in Bangladesh.

Screening for phenylthiocarbamide (PTC) taste insensitivity was performed and PTC taste threshold values using 13 solutions were obtained for 102 newly detected male diabetics and 103 male non-diabetics aged 21-40 years. The study revealed a significant difference in taste sensitivity to the bitterness of PTC crystals between the diabetics and non-diabetics, the former being less sensitive than the latter (16.7 vs. 6.8%).

Adult↗

PubMed1996

No association of PROP taster status and paternal history of alcohol dependence.

Taste sensitivity to bitter substances, including ethanol, may play a moderating role both in the initiation of drinking and in the intensity and frequency of drinking once it is initiated. A study (Pelchat and Danowski, Physiol Behav 51:1261-1266, 1992) showed an association between the capacity to taste PROP (6-n-propylthiouracil), a bitter tasting compound, and a family history of alcoholism. The implication of that finding is that family-history-negative individuals may be protected from early initiation of drinking or heavy consumption of alcohol once drinking is initiated. The present study sought to replicate those findings by using direct interview methods (versus history methods) to obtain alcohol use and alcohol problem information from the parents of "at risk" individuals and by examining a larger number of subjects. A bimodal distribution of the ability to taste PROP was found, similar to that observed in the general population. No association was found between the ability to taste PROP and a paternal history of alcoholism, regardless of the taste threshold employed or after controlling for several potentially confounding variables. A lack of association with alcoholism risk was also observed for subjects' self-reports of reasons for drinking or not drinking alcohol based upon taste preference: high-risk and low-risk for alcoholism groups were not distinguished by either a stated preference for the taste of alcohol as a reason for drinking or a stated dislike for the taste of alcohol as a reason for limiting drinking. Thus, neither taste sensitivity for PROP nor the palatability of ethanol appear to influence the choice to drink among adolescent and young adult individuals at high risk for developing alcohol-related problems.

Adolescent↗

PubMed1987

Increased aversion to bitter-tasting fluids in the Brattleboro rat.

The large daily water intake of Brattleboro rats with diabetes insipidus (BDI) is believed to be due to the volume of depletion caused by their lack of circulating anti-diuretic hormone. However an increased fluid consumption cannot necessarily be interpreted as an increased behavioural drive to drink. In order to examine these rats' motivation to drink, quinine at various concentrations was given in the drinking water as sole fluid source to BDI rats and rats of the parent Long Evans (LE) strain, and their fluid balance after twenty-four hours was determined. Brattleboro rats reduced their fluid intakes significantly more than the control LE rats at the highest concentration of drug used (100 mg/l), suggesting a decreased motivation to drink. A two bottle preference test for quinine showed that the BDI rats actually have a higher taste threshold for the drug in solution in drinking water than the control LE rats. This suggests that the increased aversion to quinine in solution when it is the sole drinking source cannot be due to the BDI rats tasting the quinine at a lower concentration than the LE animals. Nor are greater toxic effects of quinine in BDI rats likely to account for the different drinking responses when presented with quinine solutions, since intragastric administration of the drug had no effect on water consumption in these animals. When BDI rats were given bitter-tasting sucrose octa-acetate solutions as their sole drinking source, drinking was again drastically reduced. However LE rats actually increased their fluid consumption when given sucrose octa-acetate showing a preference for this substance in solution to tap water.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

[Differential taste sensitivity of Pygmy and non-Pygmy populations of the dense forest, Sudanese and Eskimos, in relation to their biochemical environment].

Significant differences of taste thresholds for different sugars, salt, organic acids, and bitter products, observed in human populations in contrasted environments, are related to potential variations of traditional diet. In this respect, biochemical composition of the environment would be the major selective pressure for taste perception.

Adult↗

PubMed1986

Taste and aging.

Taste thresholds are known to rise with age, but the status of suprathreshold sensations is less clear. The present study assessed the perceived intensities of sodium chloride, sucrose, citric acid, and quinine hydrochloride with the method of magnitude matching. This method takes advantage of participants' ability to judge sensations from two sensory continua (in this case taste intensity and loudness) on a common intensity scale, in effect, matching them. Elderly and young adults matched most of the moderate and strong tastes to the same loudnesses. If the sounds were equivalently loud to elderly and young adults, then these results would mean that moderate and strong tastes were also equivalently strong, that is, taste sensation had not faded for our elderly adults. Water and dilute taste solutions were matched to louder sounds by elderly than young participants. This may reflect the presence of a mild dysgeusia (background taste).

Acoustic Stimulation↗

PubMedDate not supplied

Taste and smell losses in normal aging and disease.

OBJECTIVE: To review the scientific literature on the alterations in the senses of taste and smell in the elderly, including causes, diagnosis, prognosis, and treatment. DATA SOURCES: Original reports and reviews obtained through MEDLINE searches from 1966 through June 1997 using the MeSH headings of "taste," "taste buds," "taste disorders," "taste thresholds," "smell," "odors," "aged," and "aging." Articles frequently cited in reference lists were also included. STUDY SELECTION: All articles were reviewed, tabulated, and summarized. DATA EXTRACTION: Criteria for extraction included data quality and validity, statistical treatment of the data, venue of publication, and relevance to clinical care. CONCLUSION: Losses of taste and smell are common in the elderly and result from normal aging, certain disease states (especially Alzheimer disease), medications, surgical interventions, and environmental exposure. Deficits in these chemical senses cannot only reduce the pleasure and comfort from food, but represent risk factors for nutritional and immune deficiencies as well as adherence to specific dietary regimens. Chemosensory decrements can lead to food poisoning or overexposure to environmentally hazardous chemicals that are otherwise detectable by taste and smell. Use of flavor-enhanced food can increase enjoyment of food and have a positive effect on food intake and immune status.

Aged↗

PubMed1989

Phenylthiocarbamide taste sensitivity revisited: complete sorting test supports residual family resemblance.

Phenylthiocarbamide (PTC) taste thresholds were determined in 100 nuclear families using the complete sorting test. Segregation analysis using the mixed model suggested that the variability in PTC thresholds is controlled by a major locus with incomplete dominance as well as by a multifactorial component with significant residual heritability. Such a model explained nearly 96% of the variance, leaving only 4% of the variance in thresholds arising from measurement error and other environmental factors.

Adolescent↗