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PubMed1998

Attention and the detectability of weak taste stimuli.

Subjects detected weak solutions of sucrose or citric acid under conditions in which attention was directed toward one of the tastants or the other. Detection thresholds were measured using an adaptive, forced-choice procedure, with a three-down one-up rule, which computer simulations suggest should be more reliable than the popular two-down one-up rule. The thresholds were modestly but systematically lower for attended tastants than for unattended ones. Similar results have been reported in other sense modalities, including vision (greater sensitivity to stimuli presented to attended versus unattended spatial locations) and hearing (greater sensitivity to stimuli presented at attended versus unattended sound frequencies). Taken together, the findings are consistent with a general hypothesis regarding attention in sensory systems: gains or losses in detectability occur when a central attentional mechanism (or, conceivably, a preattentive mechanism) selectively and preferentially monitors signals arising from particular subsets of peripheral neural inputs.

Adolescent↗
PubMed2005

[Age-related changes in renewal of taste bud cells and expression of taste cell-specific proteins in mice].

It is known that taste sensitivities change throughout life and they decline with aging. We have also found that both detection and recognition thresholds of taste were significantly elevated in aged persons, while oral somatic sensations hardly changed. To elucidate the peripheral mechanisms of the decline of taste sensitivities with age, we first investigated age-associated changes in cell renewal of taste buds in the circumvallate papillae of ddY mice, because one of the major characteristic differences of taste receptors from somatosensory receptors is a continual turnover of cells. In addition, we examined the expression patterns of taste cell-specific proteins such as protein gene products 9.5 (PGP 9.5) and gustducin, and ultrastructure of taste buds which may change resulting from the change of turnover rate. As a reference, we also used mice in the developing stage. The rate of cell renewal was examined using 5-bromo-2'-deoxyuridine (BrdU), which is incorporated in DNA during the S-phase of cells. BrdU and the proteins were detected immunohistochemically and the ultrastructure was investigated by electron microscopy. The aged mice demonstrated a delayed cell renewal and highly vacuolated cytoplasm in taste buds, while they showed no change in PGP 9.5-immunoreactive cells and an increase in gustducin-immunoreactive cells compared with young adult mice. In contrast, the developing mice showed a higher rate of cell turnover and rapid increase of PGP 9.5- and gustducin-immunoreactive cells reaching the mature level in 3 weeks after birth. The changes observed in the present study in aged mice may be related to the decline in taste sensitivity with aging.

Aging↗
PubMed1994

Smell acuity for acetone and its relationship to taste ability to phenylthiocarbamide in a Nigerian population.

Acetone smell sensitivity and phenylthiocarbamide taste sensitivity thresholds have been measured simultaneously for 970 Nigerians (542 males and 428 females) using modified sorting techniques. The distribution was bimodal in both cases and the frequency of subjects with high smell acuity for acetone was 9.6% while that of non-tasters was 12.60% with a gene frequency, as computed by maximum likelihood methods, of 0.355 +/- 0.015. Females showed a higher frequency for smell sensitivity to acetone but a slightly lower frequency of non-tasters compared to males. Acetone smell sensitivity and PTC with high smell acuity for acetone were tasters while 30.28% of subjects least sensitive taste ability decreased with age in the overall population. All the subjects least sensitive to acetone were non-tasters, a significantly higher proportion than in the overall population. The correlation between acetone smell acuity and phenylthiocarbamide taste ability demonstrates a strong allelic association. All the 94 individuals with high smell acuity for Acetone were tasters for phenylthiocarbamide.

Acetone↗
PubMed1995

[Whole mouth gustatory test (Part 1)--basic considerations and principal component analysis].

The whole mouth method gustatory test is a simple gustatory test. It can be applied easily, and can be used to assess overall taste which a subject is supposed to be feeling. In the present study, a new series of taste solutions for the use in the whole mouth gustatory test was prepared. In order to determine the normal range of gustation and relationships between each taste solution, gustatory threshold tests were conducted on 123 healthy volunteers (17-22 years old). The series of taste solutions represented 4 tastes, i.e., sweet, salty, sour, and bitter, and was prepared using sucrose, salt, tartaric acid and quinine, respectively. Recognition thresholds measured for each taste solution yielded normal ranges i.e., 0.0165 mol/l for the sweet solution, 0.0316 mol/l for the salty solution, 0.000734 mol/l for the sour solution, and 0.0000203 mol/l for the bitter solution which were almost the same as those published. The average thresholds obtained for all solutions were at almost always at the middle concentration level, i.e., level 6. Thus, this method can serve as a standard method of performing the whole mouth taste test. Principal component analysis of the thresholds obtained revealed that the primary component mainly demonstrated taste detection function, and that it could more or less be represented by the simple sum of each detection threshold. The analysis also showed that approximately 90% of taste threshold variation is explained by the 4 principal components. These findings provide further evidence that these four tastes comprise the basic elements of taste.

Adolescent↗
PubMed1992

Methyl xanthine, adenosine, and human taste responsivity.

The influences of three methyl xanthines (MX) on human taste responsivity, caffeine, theophylline, and theobromine, were examined using blind control procedures. Taste responsivity in the same subjects was determined using the matching procedure described by Schiffman (Study 1) and the whole-mouth procedure described by Sheperd (Study 2). In each study, the duration of MX pretreatment necessary to enhance taste responsivity was examined. No potentiation of overall- and taste-quality specific intensity ratings was observed for any tastant, independent of test procedure, type, and concentration of MX pretreatment, or length of MX pretreatment. Taste intensity ratings, especially for NaCl, were higher following pretreatment with water than methyl xanthine or adenosine combined with caffeine. Adenosine, added at several concentrations to caffeine pretreatments, influenced neither taste responsivity nor taste intensity ratings.

Adenosine↗
PubMed1981

An examination of intertrial interval and gender influences on sucrose detection thresholds established by a modified staircase procedure.

The influence of intertrial interval durations ranging from 7 to 30 s upon sucrose detection thresholds of sixteen subjects was investigated by means of a modified staircase procedure with intertrial rinses. In addition, the influence of the sex of the subject was examined. Neither the intertrial interval nor the sex of the subject significantly affected sucrose detection thresholds. The results suggest that, in sucrose detection threshold studies using the present procedure, one can employ intertrial intervals as short at 7 s without significantly affecting the threshold value.

Adult↗
PubMed1985

Electrogustometry in hemodialysis patients.

Serous zinc levels and electrogustometry were studied on thirty patients undergoing periodic hemodialysis. After dialysis a better electrogustometric threshold (p less than 0,05) and also higher serous zinc levels were found. The two parameters showed no significant correlation. These results are suggestive of a toxical damage of taste receptors in the chronic renal failure.

Adolescent↗
PubMed1995

[Electric gustatory threshold in diabetics and its clinical significance].

Electrogustometry was performed in diabetics and the correlation between the electric gustatory threshold and clinical factors of the patients (age, disease period and diabetic complications) were evaluated (n = 50). The results obtained were as follows: 1. The electric gustatory threshold rose with aging. The patient age range for further analysis was confined to 50 approximately 69 years old (n = 34) to exclude age dependency. 2. The patients with longer disease histories tended to show a higher electric gustatory threshold, indicating that taste abnormalities in diabetics progress with disease duration. 3. Elevation of the electric gustatory threshold in diabetics was observed before onset or at the earliest stage of the three major complications (diabetic neuropathy, retinopathy and nephropatho), and the threshold rose further with the progression of diabetic complications. Thus, the electric gustatory threshold is a sensitive indicator of diabetic nephropathy and was demonstrated to be a remarkably useful indicator for the prevention of diabetic complications, since it allows detection of the three major diabetic complications at their earliest stages.

Adult↗
PubMed1975

[An improved and practical electrogustometer].

Basic considerations in the construction of an electrogustometer led to the use of electronically regulated equipment. The changing body resistence is automatically regulated, but the electric voltage of 220 volts AC necessitated special precautions. The decibel scale as proposed by Tomita seems the most convenient. The range of stimulation of 3-318 muA and the 4 dB current increment, which is regarded as the lowest pathological difference between the thresholds of the two sides of the tongue, made this equipment in practice very convenient.

Electrophysiology↗
PubMed2007

A complex relationship among chemical concentration, detection threshold, and suprathreshold intensity of bitter compounds.

Detection thresholds and psychophysical curves were established for caffeine, quinine-HCl (QHCl), and propylthiouracil (PROP) in a sample of 33 subjects (28 female mean age 24 +/- 4). The mean detection threshold (+/-standard error) for caffeine, QHCl, and PROP was 1.2 +/- 0.12, 0.0083 +/- 0.001, and 0.088 +/- 0.07 mM, respectively. Pearson product-moment analysis revealed no significant correlations between detection thresholds of the compounds. Psychophysical curves were constructed for each bitter compound over 6 concentrations. There were significant correlations between incremental points of the individual psychophysical curves for QHCl and PROP. Regarding caffeine, there was a specific concentration (6 mM) below and above which the incremental steps in bitterness were correlated. Between compounds, analysis of psychophysical curves revealed no correlations with PROP, but there were significant correlations between the bitterness of caffeine and QHCl at higher concentrations on the psychophysical curve (P<0.05). Correlation analysis of detection threshold and suprathreshold intensity within a compound revealed a significant correlation between PROP threshold and suprathreshold intensity (r=0.46-0.4, P<0.05), a significant negative correlation for QHCl (r=-0.33 to -0.4, P<0.05), and no correlation for caffeine. The results suggest a complex relationship between chemical concentration, detection threshold, and suprathreshold intensity.

Adult↗
PubMed1990

Plasma retinol transport system and taste acuity in patients with obstructive jaundice.

A study was conducted to elucidate the correlation between the plasma retinol transport system and taste acuity in patients with obstructive jaundice (OJ). Plasma levels of retinol, retinol-binding protein (RBP), transthyretin (TTR) and holo-RBP (retinol-RBP complex unbound to TTR), as well as the threshold of taste acuity, were determined in 8 cases with OJ (6 cases with common bile duct cancer and 2 cases with pancreas head cancer) and in 20 apparently healthy volunteers. These parameters were also measured serially in patients with OJ before and after percutaneous transhepatic biliary drainage (PTBD). Plasma levels of retinol, RBP and TTR were significantly decreased in every patients with OJ as compared with healthy controls, whereas changes in holo-RBP levels were not consistent. Taste acuity was found to be reduced in patients with decreased holo-RBP levels, while the acuity was preserved well in patients whose holo-RBP levels remained normal. Impaired taste acuity was rapidly improved in every patients after treatment with PTBD, significantly correlating with the recovery of plasma RBP and holo-RBP levels, and with the reduction of plasma total bilirubin levels. These results suggest that taste acuity is affected by the plasma retinol transport system, including serum levels of holo-RBP, from which retinol is delivered, presumably through a receptor-mediated manner, to the taste buds.

Adult↗
PubMed1986

[Taste perception in fasting overweight patients].

In 20 patients with a heavy overweight in the course of a fasting cure at 5 different moments gustation tests were carried out: in satiated state, in the acute fasting state and during the building-up phase. It could be proved that the thresholds in the acute fasting state are significantly lower than in the satiated state. Also in the building-up phase this tendency is pointed at. An efferent influence on the receptors evoked by hunger is discussed as cause. A direct relation between the change of the gustation sensitivity and individual metabolic parameters did, however, not develop under the experimental conditions given.

Diet, Reducing↗
PubMed1979

Taste acuity of the human palate. II. Studies with electrogustometry on subjects in different age groups.

The electrical taste acuity on the hard and soft palate and the tip of the tongue was determined in 140 subjects aged 13-81 years using an electrogustometer constructed for the study. The possible influence of several variables including age, sex, wearing of a full upper denture, smoking as well as medical and social factors on the threshold values was also studied. Taste perception was demonstrated on the soft palate and on an area of the hard palate close to the junction of the hard and soft palate in most subjects. No perception of the electrical taste was found in eleven subjects (8%) on either the hard or the soft palate and in an additional 33 subjects (24%) on the hard palate alone and 2 subjects (1%) on the soft palate alone. The taste thresholds on the hard palate were very high compared to those on the soft palate and those on the tongue. Older subjects generally had higher thresholds than did younger subjects and the differences were greater for the thresholds on the hard and soft palate than for those on the tongue. No statistically significant differences in threshold values were found between women and men, denture wearers and non-denture wearers or smokers and non-smokers.

Adolescent↗