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PubMed1998

The taste of sodium.

Sodium is crucial to physiological function. The responsibility for detecting it is assumed by the taste system, which devotes perhaps one quarter of its resources to the task. Sodium is transduced by passage into a subset of receptor cells, whose activity is relayed to the brain through a discrete gustatory channel. Responses in hindbrain, thalamus, and gustatory cortex identify the quality and concentration of sodium on the tongue. Coding of reinforcement may begin with the pons and ventral forebrain, particularly the lateral and medial hypothalamic nuclei. When body stores are sufficient, behavioral preference for sodium is mild, encompassing low concentrations and marked by weak avidity. This languid response disappears during sodium shortages. Avidity increases, and hypertonic concentrations are most preferred. This behavioral change may result from altered responsiveness in sodium-specific neurons that offer the sodium signal access to mechanisms of reinforcement. Thus, the taste system detects and recognizes sodium, and accords it a reward value commensurate with the needs of the animal.

Animals↗
PubMed1999

Glutamate and the UMAMI taste: sensory, metabolic, nutritional and behavioural considerations. A review of the literature published in the last 10 years.

Monosodium glutamate (MSG) is used increasingly often in processed foods and in home cooking in the Western world. This substance is responsible for a pleasurable taste sensation, the Umami taste. This review covers recent developments in sensory studies of glutamate effects, and traces the Umami taste from sensory receptors on the tongue to the brain. The metabolism of glutamic acid, as revealed from recent literature, is described. A specific section is devoted to safety issues. In addition, effects of glutamic salts on nutrition and ingestive behaviours are shown to be potent. Animal and human works are treated separately, with special attention to the specific methods used in both cases. Future areas of research include further investigation of sensory physiology, role of glutamate as an excitatory substance in the brain, acquisition of food likes and impact on long-term food selection, food intake, and body weight control.

Animals↗
PubMed1983

Taste aversion learning: simulation of interference with the gustatory cue during conditioning.

Rats were taught an aversion to a sucrose taste cue of varying strengths. The concentration of the sucrose solution was either, 10, 7.5, 5, 2.5, 1, 0.5, or 0.25% which the animals drank for 5 min. Thirty minutes later they were poisoned with lithium chloride. On the test day all animals had access to a 10% sucrose solution regardless of the concentration they had drunk on the conditioning day. Animals conditioned with a 10, 7.5, or 5% sucrose cue subsequently displayed an identically strong aversion to the 10% cue. Only those animals conditioned with a sucrose cue which was 1% or less displayed a significantly weaker aversion to the 10% cue. The results are discussed in terms of the theory that interference with taste aversion learning by such agents as pentylenetetrazol and electroconvulsive shock may have their effect by disrupting the gustatory engram. If this assumption is correct then it suggests that the memory of the gustatory cue may be stored, at least prior to poisoning, in a quite labile state and an apparently limited disruption of taste aversion learning may in fact represent a substantial amnesic effect.

Animals↗
PubMed1988

Chronic sweet intake lowers pain thresholds without changing brain mu- or delta-opiate receptors.

Sprague-Dawley rats drank sweetened (3% dextrose + 0.144% saccharin, w/v) or unflavored water for 18 days and subsequent pain reactivity was assessed using a hot plate. Compared to the rats that consumed unflavored water, the rats that consumed sweet water responded more quickly on the hot plate indicating that their threshold for pain was lowered. Another group of rats given identical exposure to the fluids had their brains prepared for measuring opiate receptor binding using the delta-receptor ligand [3H]D-Ala-D-Leu-enkephalin ([3H]DADLE) and the mu-receptor selective ligand [3H]Tyr-D-Ala-Gly-MePhe-Gly-ol ([ 3H]DAGO). Binding of these opiates to mu- and delta-receptors in the cerebral cortex, striatum, hippocampus, hypothalamus, brain stem, and remaining brain regions was the same for the rats that drank sweet fluids and those that drank unflavored water. These findings suggest that drinking sweet fluids lowers pain thresholds but does not alter mu- and delta-receptors.

Animals↗
PubMed1999

The role of the agranular insular cortex in working memory for food reward value and allocentric space in rats.

The present experiment examined the effects of quinolinic acid (125 mM) lesions of the agranular insular area on working memory for food reward value and working memory for spatial locations. In both tasks a go/no-go procedure was used. Working memory for food reward value was assessed using a delayed conditional discrimination in which either a 20% or 45% sugar content cereal was associated with a reinforcement and the other cereal was not. In the spatial locations task, rats were allowed to enter 12 arms in a radial maze for a food reinforcement. Of the 12 arm presentations, three or four arms were presented for a second time in a session which did not contain a reinforcement. The number of trials between the 1st and 2nd presentation of an arm ranged from 0 to 6 (lags). Working memory was assessed by the latency to enter an arm during the 2nd presentation. In the food reward value task, agranular insular lesions produced memory deficits in a delay-dependent manner. In contrast, agranular insular lesions did not impair working memory for spatial locations. These results add to accumulating evidence suggesting that different types of working memory are distributed across separate prefrontal subregions.

Animals↗
PubMed2002

De Gustibus: time scale of loss and recovery of tastes caused by radiotherapy.

PURPOSE: To quantify the prevalence and distress of taste loss at different intervals after radiotherapy (RT) for head and neck cancer. MATERIALS AND METHODS: In four different groups of head and neck cancer patients (73 patients in total), taste loss and distress due to taste loss were evaluated by taste acuity tests and taste questionnaires. Group 1 (n=17) was analyzed prior to RT. Groups 2 (n=17), 3 (n=17) and 4 (n=22) were at 2, 6 and 12-24 months after treatment, respectively. A cross-sectional analysis was performed between these four groups. RESULTS: Prior to initiation of RT (group 1), partial taste loss was observed in 35, 18 and 6% of patients for bitter, salt and sweet, respectively. At 2 months after RT (group 2), taste loss (partial or total) was seen in 88, 82, 76 and 53% for bitter, salt, sweet and sour, respectively. At 6 months (group 3), partial taste loss was seen in 71, 65, 41 and 41% (bitter, salt, sweet, sour) and after 1-2 years (group 4) in 41, 50, 27 and 27% (bitter, salt, sweet, sour). Distress caused by taste loss was most frequent in group 2 (82%). CONCLUSIONS: In this study, loss of taste after RT was found to be most pronounced after 2 months. Bitter and salt qualities were most impaired. Gradual recovery was seen during the first year after treatment. Partial taste loss still persisted 1-2 years after treatment and was responsible for slight to moderate discomfort.

Cross-Sectional Studies↗
PubMed1984

Isohedonic tastes support a two-dimensional hypothesis of palatability.

The hypothesis that tastes activate two systems of palatability processing was tested by examining the ingestive and aversive fixed-action patterns (FAPs) elicited by equally preferred tastes. Berridge and Grill (1983) reported that the probability of occurrence of aversive FAPs could be increased without producing a reciprocal reduction in the probability of ingestive responses. This independence of ingestion and aversion was confirmed, and it was shown that the effect extends to measures of the actual quantity, as well as the probability, of the FAPs. It was further shown that ingestive and aversive FAPs could be increased together by simultaneously increasing the sucrose and quinine concentration of a taste. Equal preference between tastes may therefore need not imply identical hedonic evaluations, but rather simply an equivalent balance between ingestive and aversive systems. These data provide support for a two-dimensional hypothesis of palatability processing.

Animals↗
PubMed1985

Stimulus range influences intensity and hedonic ratings of flavour.

Five concentrations of an artificial orange drink were presented for sensory evaluation in three overlapping concentration ranges. Three sensory panels, each of 30 subjects, rated the concentrations for intensity of flavour (intensity scale), relation to ideal flavour intensity (ideal-point scale), and pleasantness (hedonic scale). Except for the two extreme concentrations, neither of which was presented in more than one range, in all three response tasks the mean rating for a given concentration varied with the concentration range in which it was presented. However, the mean ratings showed good correspondence across response tasks (e.g. the concentration perceived as "moderately sweet" on the intensity scale was perceived as "just right" on the ideal-point scale and of maximal pleasantness on the hedonic scale), suggesting a link between the intensity and hedonic dimensions of sensory experience.

Attitude↗
PubMedDate not supplied

Clinical evaluation of taste.

Partial loss of taste function can take a variety of forms. Losses can be specific to one taste quality or to one tongue locus. In addition, the shapes of psychophysical functions can be altered so that taste intensity no longer grows normally with concentration. Magnitude matching, an efficient psychophysical scaling method (based on magnitude estimation of stimuli from two sensory continua), can provide a relatively quick assessment of a patient's ability to taste the four taste qualities--sweet, salty, sour, and bitter. When taste intensity and loudness are scaled in the same session, a person with normal hearing who has taste loss will match taste intensities to abnormally weak sounds. Spatial losses are detected by placing pieces of filter paper soaked in taste solutions on specific tongue loci. Dysgeusia, the presence of a chronic taste in the mouth, can result from abnormal substances in the mouth (e.g., via saliva or from poor oral hygiene) or can reflect disorders of the central nervous system.

Humans↗
PubMed1998

Application of taste reactivity to study the mechanism of alcohol intake inhibition by the tachykinin aminosenktide.

Tachykinin NK-3 receptor agonists reduce alcohol intake in alcohol-preferring rats; the nucleus basalis magnocellularis (NBM) is highly sensitive to their effect. Tachykinins and their receptors are widely distributed in gustatory pathways and NK-3 receptor agonists have been reported to modify taste reactivity to salt solutions in rats. The present study evaluated whether the TK NK-3 receptor agonist aminosenktide (NH2-SENK) influences taste reactivity to ethanol solutions. Genetically selected Marchigian Sardinian alcohol-preferring (msP) rats were employed. In response to the intraoral infusion (0.8 ml in 1 min) of 10, 20, 40, or even 60% ethanol solution, ethanol-naive rats showed a large number of ingestive reactions and a much lower number of aversive reactions. Two min before the intraoral infusion of 10 or 40% ethanol, NH2-SENK was injected either into the lateral ventricle (LV) or into the NBM. Doses of NH2-SENK that markedly reduce alcohol intake, 125 ng/rat into the LV or 5 ng/site into the NBM, did not modify the ingestive reactions and, in some instances, reduced the aversive reactions to ethanol solutions in ethanol-naive rats. Injections of 125 ng/rat into the LV failed to modify taste reactions in ethanol-experienced rats. The present results show that msP rats have an innate hedonic evaluation of ethanol solutions, even of high concentration. Moreover, they indicate that reduction of ethanol intake induced by TK NK-3 receptor agonists in alcohol-preferring rats does not depend on influences on gustatory processes.

Afferent Pathways↗
PubMed1998

The bitter with the sweet: the taste/stress/temperament nexus.

Is the tongue a window to the psyche? In rats, stress alters taste, and individual differences in taste are related to measures of emotion. The present study concerned stress-induced changes in taste and its modulation by temperament in people. College students rated saccharin's bitterness and sweetness and a tone's loudness after exposure to a mild stressor. Temperament (trait arousability, pleasure, and dominance) was assessed separately. When individual differences were ignored, stress appeared to selectively increase sensitivity to saccharin's bitterness. However, the stressor's impact was modulated by temperament: Stress nonselectively augmented stimulus magnitude ratings among highly arousable individuals; relative to high-pleasure counterparts, low-pleasure individuals gave higher bitterness ratings and lower sweetness ratings after stress. Taste does seem to provide a glimpse of the emotional life of humans and other animals and opens new avenues to the study of the biological bases of affect.

Adult↗
PubMed1998

PROP taster status and parental history of alcohol dependence.

Pelchat and Danowski [Physiol. Behav. 1992;51:1261-1266] reported an association between the ability to taste 6-n-propylthiouracil (PROP) and a parental history of alcoholism. Kranzler et al. [Alcohol Clin. Exp. Res. 1996a;20:1496-1500] previously failed to replicate these findings in a sample of subjects with only a paternal history of alcohol dependence. The present study was conducted to examine this putative association in a sample of subjects that is heterogeneous with respect to parental alcoholism history. Among the 90 alcohol-dependent subjects studied, the proportion of PROP nontasters was comparable to that observed among nonalcoholics. Analysis revealed no association of parental history with PROP taster status, even after controlling for potential confounding variables. We conclude that no reliable association exists between taste sensitivity to PROP and either a diagnosis of alcohol dependence or a parental history of alcohol dependence.

Adult↗
PubMed2002

Prediction of the bitterness of single, binary- and multiple-component amino acid solutions using a taste sensor.

The purpose of this study was to develop a quick, quantitative, prediction method for the determination of the bitterness of solutions containing one or more of five amino acids (L-isoleucine, L-leucine, L-valine, L-phenylalanine, and L-tryptophan), using an artificial taste sensor. The bitterness of various solutions containing different concentrations (1, 3, 10, 30, and 100 mM) of five amino acids, singly and in combination, was estimated using a multichannel taste sensor and compared with the results of human gustatory sensation tests with nine volunteers. The relative response electric potential patterns were similar for all five amino acids. Large sensor outputs were observed in channels 1-4 (which are negatively charged) while there were no responses in channels 5-8 (positively charged). The sensor output for channel 1, which was the largest output value, was used for prediction of bitterness. The change of membrane potential caused by adsorption (CPA), which corresponds to aftertaste, could not be used as an explanatory variable since the adsorption of the amino acids to the sensor membrane was weak and CPA values were small. The bitterness intensity scores for single, binary, and multi-component amino acid solutions, could be easily predicted on the basis of the sensor output value of channel 1 using regression analysis. Principal component analysis of the sensor output data suggested that the sourness, astringency and/or smell of the solutions also played a role in the perception of bitterness.

Amino Acids↗
PubMed1986

Basis and practice of clinical taste examinations.

Separate taste examinations of each area of gustatory innervation are necessary in clinical practice in treating patients with taste disorders. We have developed our own electrogustometer with a dB scale and qualitative and quantitative clinical gustometry using filter-paper discs (the filter-paper disc method). this paper reports on our main basic studies in this field and new insights and experience gained in connection with the two gustometry procedures. Reference is made to the gustatory pathway, innervation area on the tongue and the soft palate, the argument against the localization theory of taste, the correlation between electrogustometry and the filter-paper disc method, differential diagnosis of taste disorders using both methods and the effective use of these methods in clinical practice. The effective use of both methods of measurements is important to give the physician assurance and confidence in the diagnosis and treatment of taste disorders.

Adolescent↗
PubMed1986

Assessment of taste disorders in rats by simultaneous study of the two-bottle preference test and abnormal ingestive behavior.

Taste disorders were produced in rats by the administration of a zinc-deficient diet and assessed by two methods, i.e., observations of the subjects' behavior in terms of the two-bottle preference test and of their ingestive behavior in terms of taste differentiation. The findings of the two tests were compared, revealing a high degree of agreement. The results indicate that reliable data can be obtained from the two-bottle preference test, an examination procedure extensively applied to the study of taste disorders, as well as from observation of the rats' ingestive behavior. Thus, both methods can be used in parallel for assessing or confirming taste disorders in rats.

Animals↗
PubMed1989

Influences on taste in the area of chorda tympani nerve after transtympanic injection of local anesthetic (4% lidocaine).

Transtympanic injection of 4% lidocaine (TTIL) is a unique procedure to treat tinnitus. Some physicians in Japan have been adopting this procedure to treat tinnitus. It has several complications, and safety standards of this procedure have not yet been established. Among the complications, we focused on "transient taste disturbance" after TTIL, because there have been no detailed reports on this subject. We examined the taste sensation in the area of the chorda tympani nerve before and after TTIL by applying electrogustometry with dB scale (EGM) and filter-paper disc method (FPD method). For a control, we used transtympanic injection of 0.4% dexamethasone (TTIS). After TTIL, transient pathway insufficiency on chorda tympani nerve was observed both in the EGM and the FPD methods, but this pathway insufficiency recovered within 24 h. Some patients felt spontaneous abnormal bitter taste sensation in the oral cavity after TTIL, but the reason for this phenomenon could not be determined.

Adult↗
PubMed1993

Assessment of inferior alveolar and lingual nerve disturbances after dentoalveolar surgery, and of recovery of sensitivity.

In a follow-up of 1107 dentoalveolar operations in the postcanine region, 24 (2.2%) temporary sensitivity disturbances of the inferior alveolar nerve and 16 (1.4%) of the lingual nerve were found. Permanent disturbances were not present. Complete recovery had occurred by 6 months in all cases. The incidence of temporary sensitivity disturbances depended on the different surgical interventions performed. For evaluation and follow-up purposes, a computer-aided pain and thermal sensitivity (PATH) tester was used. By PATH testing, spontaneous recovery can already be ascertained at the third or fourth postoperative month.

Adolescent↗