Relation of cue to consequence in rats: effect of recuperation from illness.
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Acoustic Stimulation↗
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Results for “taste perception”
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Taste-evoked responses to sweeteners in the nucleus of the solitary tract differ between C57BL/6ByJ and 129P3/J mice.
C57BL/6ByJ (B6) and 129P3/J (129) mice have different alleles of Tas1r3, which is thought to influence gustatory transduction of sweeteners, but studies have provided conflicting results regarding differences in sweetness perception between these strains. Single-unit taste-evoked activity was measured in the nucleus of the solitary tract (NST) in anesthetized B6 and 129 mice to address this controversy and to provide the first electrophysiological characterization of this nucleus in mice. Neurons had properties similar to those of NST cells in other species, including mean breadth-of-tuning of 0.8 +/- 0.0. There were no strain differences in neural responses at 600 or 900 ms after onset, but, with a 5 s evoked period, responses to the sweeteners sucrose, maltose, acesulfame-K, SC-45647, and D-phenylalanine were significantly larger in B6 relative to 129 mice. The strains did not differ in their mean response to NaSaccharin, but it evoked an across-neuron pattern of activity that was more similar to that of sucrose and less similar to that of NaCl in B6 mice compared with 129 mice. Neurons were classified as sucrose, NaCl, or HCl responsive, with the former more common in B6 than 129 mice. Relative to other neurons, sucrose-responsive cells had delayed but more sustained sweetener responses in both strains. The results suggest that B6 mice perceive some sweeteners as more intense, but NaSaccharin as sweeter and less salty, relative to 129 mice. Furthermore, activity evoked by sweeteners includes a phasic response sent to different NST cells than a later tonic response, and only the latter differs between B6 and 129 mice.
Animals↗
Fat perception is related to PROP taster status.
Individuals who are sensitive to the bitter compounds phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) are also more sensitive to selected bitter and sweet substances, to sharp-tasting foods, and to the trigeminal irritant capsaicin. PTC/PROP tasters have a greater density of fungiform taste papillae and it is speculated that PTC/PROP tasters also have more trigeminal innervation. Because oral texture perception is also mediated, in part, by trigeminal fibers, it has been proposed that individual differences in fat perception might also be linked to PTC/PROP taster status and taste bud density. This work tests the hypothesis that individuals who are PROP tasters: 1. have a higher density of fungiform papillae; 2. are more sensitive to capsaicin; and 3. have increased ability to discriminate differences in fat content in salad dressing. Individual subjects were classified as PROP nontasters, medium tasters, or supertasters (n = 25 per group) by comparing their psychophysical function for PROP to that of NaCl. Papillae densities (papillae/cm2) were significantly different among the 3 taster groups (p < or = 0.0001), and were highest among the supertasters. Both medium tasters and supertasters perceived more oral burn from capsaicin than did nontasters at concentrations of 50, 70, and 100 ppm (p < or = 0.0001). Medium tasters and supertasters could also discriminate differences in fat content between 40% fat and 10% fat salad dressings (p < or = 0.005), but the nontasters could not. These data provide the first published evidence that fat perception can be linked to genetic and anatomical differences between individuals.
Adolescent↗
Sickness-induced learning in chicks.
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Animals↗
Revisiting sugar-fat mixtures: sweetness and creaminess vary with phenotypic markers of oral sensation.
Genetic variation in oral sensation presumably influences ingestive behaviors through sensations arising from foods and beverages. Here, we investigated the influence of taste phenotype [6-n-propylthiouracil (PROP) bitterness, fungiform papillae (FP) density] on sweet and creamy sensations from sugar/fat mixtures. Seventy-nine subjects (43 males) reported the sweetness and creaminess of water or milk (skim, whole, heavy cream) varying in sucrose (0-20% w/v) on the general Labeled Magnitude Scale. Sweetness grew with sucrose concentration and when shifting from water to milk mixtures--the growth was greatest for those tasting PROP as most bitter. At higher sucrose levels, increasing fat blunted the PROP-sweet relationship, whereas at lower levels, the relationship was effectively eliminated. Perceived sweetness of the mixture exceeded that predicted from the sum of components at low sucrose concentrations (especially for those tasting PROP most bitter) but fell below predicted at high concentrations, irrespective of fat level. Creaminess increased greatly with fat level and somewhat with sucrose. Those tasting PROP most bitter perceived greater creaminess in the heavy cream across all sucrose levels. Perceived creaminess was somewhat lower than predicted, irrespective of PROP bitterness. The FP density generally showed similar effects as PROP on sweetness and creaminess, (but to a lesser degree) and revealed potential taste-somatosensory interactions in weakly sweet stimuli. These data support that taste phenotype affects the nature of enhancement or suppression of sweetness and creaminess in liquid fat/sugar mixtures. Taste phenotype effects on sweetness and creaminess likely involve differential taste, retronasal olfactory, and somatosensory contributions to these perceptual experiences.
Adult↗
Comparison between neural and psychophysical recordings of taste stimulations.
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Chorda Tympani Nerve↗
Smart chemical taste sensor for determination and prediction of taste qualities based on a two-phase optimized radial basis function network.
A novel, smart, chemical taste sensor that realistically mimics the behavior of the human gustatory system is described. The taste sensor consists of an array of electrochemical sensors that represent the gustatory receptors on the human tongue, and a two-phase optimized radial basis function network (RBFN) to represent the human brain, which comprehensively analyzes the gustatory stimulation and judges the overall taste. In the illustrated model, eight electrodes were fabricated to determine the eight major taste-causing substances, Na+, K+, Cl-, H+, sucrose, glucose, glutamate, and caffeine. The detected signals were fed to a two-phase RBFN optimized by the implementation of a basis optimization algorithm and weight decay term for appropriate data processing. The first phase of the two-phase RBFN quantifies the amount of taste-causing substances in food samples from the responses of the electrodes. These results are then fed to the second phase, which correlates the amount of substances with the overall taste. The final output is scored on a scale of 1-5 for each of the five basic tastes sensed by the human gustatory system, which are saltiness, sourness, sweetness, bitterness, and umami. The constructed network estimated the intensity of the basic tastes of 30 drink varieties with an average relative error of 7.0% compared to the human scores. The network could also estimate the variance in the human sensory perception. Moreover, the sensor successfully predicted the interactions of tastes such as suppression of bitterness by sweetness and enhancement of umami by saltiness, which are illusions sensed by the human gustatory system. With these abilities, the novel taste sensor can be considered as a quantitative yet humanlike sensor with a great potential for practical applications.
Algorithms↗
Ipsi- and bilateral interactions in taste.
In two experiments, the integration over spatial extent in taste was investigated for threshold sensitivity to NaCl and for suprathreshold intensity perception of saltiness. The area of stimulation was doubled by adding either an ipsilateral or a bilateral stimulus. The two stimuli could be of equal or unequal intensity. The data showed that at threshold level a probability summation model applied to all bilateral and most of the ipsilateral stimulus combinations. Probability summation failed to predict detection probability when two stimuli with different intensities were presented at the same tongue side. For suprathreshold stimuli, the magnitude of the saltiness sensation as estimated by a line-length method depended on the level of stimulation. The possible peripheral interaction mechanisms and central factors contributing to the taste response were discussed.
Adult↗
Infantile autism--an hypothesis.
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Auditory Perception↗
Perceptive properties of the multi-site electrical microstimulation of the olfactory bulb in the rat.
Electrical microstimulation of the olfactory bulb in different locations has been shown to provide water-deprived rats with discriminative cues for selecting a palatable solution without tasting it in a two-choice test. Some perceptive properties of bulbar electrical stimulation were investigated. It was shown that the perceptive effect evoked by stimulating a given site could be recognized when this site was stimulated together with several others. The animals' perception of multi-site stimulation patterns seems therefore to be analytical rather than synthetic. Discrimination of stimulation patterns did not require presentation of concurrent patterns inside a short time interval. Identification of a multi-site pattern was possible when this pattern was presented alone in a test session. Individual characteristics of bulbar microstimulation appear to be perceived absolutely rather than differentially. A good retention of the discrimination learning of specific stimulation patterns was observed. Animals could identify stimulation patterns after complete interruption of the training for 17 days. The results are discussed with reference to the properties of the natural stimulation of the olfactory system.
Animals↗
Effects of exposure to unrealistic promises about dieting: are unrealistic expectations about dieting inspirational?
OBJECTIVE: The false-hope syndrome suggests that unrealistic expectations about dieting set dieters up for failure and then promote renewed efforts at weight loss. Many dieters believe the inflated promises typical of diet advertisements, which may be the source of at least some of their unrealistic expectations. Diet advertisements promoting unrealistic expectations were expected to inspire restrained eaters to diet and lead to enhanced self-perceptions, relative to more circumspect advertisements. METHOD: Female undergraduates rated their expectations in response to a control advertisement or to advertisements containing realistic, moderately unrealistic, or highly unrealistic promises of dieting. Participants then rated their self-perceptions and participated in an apparent "taste-test". RESULTS: Restrained eaters had higher expectations for themselves than did unrestrained eaters, and restrained and unrestrained eaters had similar expectations concerning dieting for others. Those who viewed the advertisements containing unrealistic expectations ate fewer cookies ad libitum than did those who viewed the realistic or control advertisements. DISCUSSION: This finding is consistent with the suggestion that unrealistic expectations contribute to the decision to change oneself.
Adult↗
Orbitofrontal cortex neurons: role in olfactory and visual association learning.
1. The orbitofrontal cortex is implicated in the rapid learning of new associations between visual stimuli and primary reinforcers such as taste. It is also the site of convergence of information from olfactory, gustatory, and visual modalities. To investigate the neuronal mechanisms underlying the formation of odor-taste associations, we made recordings from olfactory neurons in the orbitofrontal cortex during the performance of an olfactory discrimination task and its reversal in macaques. 2. It was found that 68% of odor-responsive neurons modified their responses after the changes in the taste reward associations of the odorants. Full reversal of the neuronal responses was seen in 25% of these neurons. Extinction of the differential neuronal responses after task reversal was seen in 43% of these neurons. 3. For comparison, visually responsive orbitofrontal neurons were tested during reversal of a visual discrimination task. Seventy-one percent of these visual cells showed rapid full reversal of the visual stimulus to which they responded, when the association of the visual with taste was reversed in the reversal task. 4. These demonstrate that of many orbitofrontal cortex olfactory neurons on the taste with which the odor is associated. 5. This modification is likely to be important for setting the motivational value of olfactory for feeding and other rewarded behavior. However, it is less complete, and much slower, than the modifications found or orbit frontal visual during visual-taste reversal. This relative inflexibility of olfactory responses is consistent with the need for some stability is odor-taste associations to facilitate the formation and perception of flavors.
Acoustic Stimulation↗
Aura phenomena during syncope.
We studied the frequency and clinical characteristics of aura phenomena in 60 patients with cardiac and 40 subjects with vasovagal syncopes. The majority (93%) of all syncope patients recalled having experienced an aura. Aura phenomena were similar in both groups and were mostly compound auras comprising epigastric, vertiginous, visual, or somatosensory experiences, but were more detailed in the noncardiac group. The localizing significance of auras preceding a syncope was generally poor. Although hard to distinguish from epileptic auras from their structure and shape, syncope-related auras lacked symptoms that are commonly reported after epileptic seizures such as tastes, smells, déjà vu phenomena, scenic visual perceptions, and speech impairments. A detailed anamnestic exploration of auras seems worthwhile in unexplained disorders of consciousness.
Adolescent↗
Burning mouth and saliva.
Stomatodynia is the complaint of burning, tickling or itching of the oral cavity, and can be associated with other oral and non-oral signs and symptoms. However, the oral mucosa often appears normal, with no apparent underlying organic cause to account for the symptomatology. The etiology is unknown, though evidence points to the participation of numerous local, systemic and psychological factors. Among the local factors, saliva may play an important role in the symptoms of burning mouth. Saliva possesses specific rheological properties as a result of its chemical, physical and biological characteristics - these properties being essential for maintaining balanced conditions within the oral cavity. Patients with burning mouth present evidence of changes in salivary composition and flow, as well as a probable alteration in the oral mucosal sensory perception related particularly to dry mouth and taste alterations. On the other hand, alterations in salivary composition appear to reflect on its viscosity and symptomatology of burning mouth. Saliva is a field open to much research related to burning mouth, and knowledge of its properties (e.g., viscosity) merits special attention in view of its apparent relationship to the symptoms of burning mouth. The present study describes our clinical experience with burning mouth, and discusses some of the aspects pointing to salivary alterations as one of the most important factors underlying stomatodynia.
Burning Mouth Syndrome↗
Use and perceived attributes of cruciferous vegetables in terms of genetically-mediated taste sensitivity.
Bitter tasting compounds in cruciferous vegetables resemble chemically the compound phenylthiocarbamide (PTC). As sensitivity to PTC is genetically mediated, it was hypothesized that this characteristic would be linked to greater sensitivity of the bitter tasting components in cruciferous vegetables, and that PTC sensitivity would be reflected in less favourable sensory perceptions and lower use of the vegetables. PTC status was determined for healthy, racially and culturally similar women, alike in foodways and aged 18-46 years. The frequency of use and perceptions of sensory, post-ingestional and social attributes of 11 cruciferous and two non-cruciferous vegetables in both raw and cooked forms were compared between the PTC tasters and non-tasters. Minimal effects of PTC status on these factors were observed. Only two vegetables showed significant differences in use--PTC non-tasters used cooked turnip and raw watercress significantly more than did PTC tasters. Perceived bitter taste and aroma did not offer an explanation for the findings. Similarly, familiarity, early exposure, and tolerance did not account for any group differences. PTC status, especially in terms of non-tasting propensity, may have some sensory-specific effects which will impact on the use of cruciferous vegetables by young and mature women, but environmental factors may offset this effect and must be considered in studies of food behaviour.
Adolescent↗
[Gustatory perceptions in children].
As soon as the end of gestation, the gustatory system is stimulated by the taste-active compounds carried by the amniotic fluid and its maturation continues until mid-childhood. Facial expressions and relative ingestion methods show that the newborn can discriminate the various taste qualities (bitter, salty, sour, sweet and umami). The range of individual responses is wide. Neonatal reactions to sweet and umami are generally considered to express pleasure. The bitter and sour stimulations lead to hedonically negative reactions. The response to salt taste is less characteristic. Overall, the attraction towards sweet and the rejection of bitter and sour tastes become more pronounced during childhood but tend to decrease in adult life. The early attraction to sweetness is reinforced by exposure to sweet stimulations. With age, the response to salt evolves towards attraction which intensity is dependent on the context and on postnatal exposures to salt. The link between gustatory sensitivity to sweet, salty and sour stimuli and food preferences is far from being clear; the sensitivity to bitter taste better explains the rejection of bitter foods, such as vegetables for instance. The development of gustatory perceptions partly depends upon experience. A better knowledge of the role of experience could help to improve the orientation and the efficacy of nutritionally-oriented food education strategies.
Adolescent↗
[The human sense of sight as information receiver and its relation to the information-receiving properties of the remaining sense organs].
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Auditory Perception↗
Capsaicin as a probe of the relationship between bitter taste and chemesthesis.
Previous studies have indicated that capsaicin, traditionally considered to be a pure chemesthetic stimulus, can evoke a bitter taste and might also cross-desensitize the tastes of some bitter and sour tastants. The purpose of the present study was to investigate further the scope and nature of capsaicin's effects on bitter taste. In Experiment 1, subjects rated the taste and burning/stinging of QSO4 (0.32 and 1.0 mM), saccharin (1.0 and 3.2 mM), urea (3.2 and 10 M), MgCl2, (0.18 and 0.56 M), PROP (0.32 mM), and sucrose (0.32 and 1.0 M) applied to the tongue tip with cotton swabs before and after 10 applications of 300 microM capsaicin. Capsaicin initially evoked a weak bitterness in some subjects that quickly diminished over repeated exposures. Following capsaicin treatment, the bitterness of QSO4, urea, MgCl2, and PROP was reduced, as was the burning sensation produced by MgCl2 and urea. In Experiment 2, we tested 29 subjects in the circumvallate (CV) region of the tongue using the same general procedure. Capsaicin induced a weak but persistent bitterness in a subset of subjects but failed to desensitize its own bitterness or that of any other tastant. Overall, the results confirm that capsaicin can both stimulate and desensitize bitter taste, but in amounts that vary for different bitter stimuli and between the front and back of the tongue. Possible reasons for these regional and stimulus-dependent differences are discussed.
Adolescent↗