Taste of time: A porous-medium model for human tongue surface with implications for early taste perception.
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ABSTRACT:
SUBMITTER: Wu Z
PROVIDER: S-EPMC7271999 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundTemporal dynamics may importantly modulate sensory perception, including taste. For example, enhanced perceived taste intensity is often observed when tastant concentration is fluctuating in pulses. The perceived intensity is higher than that of the solutions with a same averaged, but constant concentrations. Meanwhile, taste intensity often decreases with increase of tastant viscosity, despite no changes to the stimuli concentration. The mechanisms to these phenomena are not well understood, in part due to the complicated transport process of tastant through papillae, taste pores, etc. to reach the taste receptors, a cascade of events that are difficult to quantify.MethodWe computationally modeled the human tongue surface as a porous micro-fiber medium, extending a previous study and exposed it to pulsatile tastant solution (0.2 and 0.4Hz) with various added viscosity (~0.0011-~0.09 Pa⋅s).ResultsOur simulation revealed that the stimuli concentration within the papillae structure increase with pulsed stimulation, especially those with a longer period (16% increase at 0.4Hz and 23% at 0.2Hz compared to continuous stimuli) and decrease (-6%) with added viscosity. The trend matched well with measured taste perception to sucrose added apple juice in the literature (R2 > 0.97 for both low and high viscosity stimuli series). Decreased diffusivity due to the increase in viscosity, however, was not a major factor underlying this process.ConclusionThis study re-affirms the validity and accuracy of modeling human tongue surface as a porous medium to investigate taste stimuli transport processes and such peripheral transport dynamics may have significant effects on taste perception.
| S-EPMC8263469 | biostudies-literature
Project description:Background: The rise in nutrition-related morbidity and mortality requires public health intervention programs targeting nutritional behavior. In addition to socio-economical, socio-cultural, psychological determinants, taste is one of the main factors that influence food choices. Differences in taste perception and sensitivity may be explained by genetic variations, therefore the knowledge of the extent to which genetic factors influence the development of individual taste preferences and eating patterns is important for public policy actions addressing nutritional behaviors. Our aim was to review genetic polymorphisms accounting for variability in taste and food preferences to contribute to an improved understanding of development of taste and food preferences. Methods: The electronic databases PubMed, Scopus, and Web of Science were searched using MeSH in PubMed and free text terms for articles published between January 1, 2000 and April 13, 2018. The search strategy was conducted following the PRISMA statement. The quality of the included studies was assessed by the validated Q-Genie tool. Results: Following the PRISMA flowchart, finally 103 articles were included in the review. Among the reviewed studies, 43 were rated to have good quality, 47 were rated to have moderate quality, and 13 were rated to have low quality. The majority of the studies assessed the association of genetic variants with the bitter taste modality, followed by articles analyzing the impact of polymorphisms on sweet and fat preferences. The number of studies investigating the association between umami, salty, and sour taste qualities and genetic polymorphisms was limited. Conclusions: Our findings suggest that a significant association exists between TAS2R38 variants (rs713598, rs1726866, rs10246939) and bitter and sweet taste preference. Other confirmed results are related to rs1761667 (CD36) and fat taste responsiveness. Otherwise further research is essential to confirm results of studies related to genetic variants and individual taste sensitivity. This knowledge may enhance our understanding of the development of individual taste and related food preferences and food choices that will aid the development of tailored public health strategy to reduce nutrition-related disease and morbidity.
| S-EPMC6930899 | biostudies-literature
Project description:Understanding the influence of taste perception on food choice has captured the interest of academics, industry, and the general public, the latter as evidenced by the extent of popular media coverage and use of the term supertaster. Supertasters are highly sensitive to the bitter tastant propylthiouracil (PROP) and its chemical relative phenylthiocarbamide. The well-researched differences in taste sensitivity to these bitter chemicals are partially controlled by variation in the TAS2R38 gene; however, this variation alone does not explain the supertaster phenomenon. It has been suggested that density of papillae, which house taste buds, may explain supertasting. To address the unresolved role of papillae, we used crowdsourcing in the museum-based Genetics of Taste Lab. This community lab is uniquely situated to attract both a large population of human subjects and host a team of citizen scientists to research population-based questions about human genetics, taste, and health. Using this model, we find that PROP bitterness is not in any way predicted by papillae density. This result holds within the whole sample, when divided into major diplotypes, and when correcting for age, sex, and genotype. Furthermore, it holds when dividing participants into oft-used taster status groups. These data argue against the use of papillae density in predicting taste sensitivity and caution against imprecise use of the term supertaster. Furthermore, it supports a growing volume of evidence that sets the stage for hypergeusia, a reconceptualization of heightened oral sensitivity that is not based solely on PROP or papillae density. Finally, our model demonstrates how community-based research can serve as a unique venue for both study participation and citizen science that makes scientific research accessible and relevant to people's everyday lives.
| S-EPMC4035552 | biostudies-literature
Project description:Background: To measure sensory taste perception in children with an accurate and reproducible method is challenging and objective measurement methods are scarce. Objective: Aim was to characterize sensory taste perception, by measuring the number of fungiform papillae (FP) and to investigate whether the number of FP is associated with sensitivity for bitter taste and with taste preferences for sweet, salty, fatty or umami in children between 8 and 11 years of age. Design: Number of FP was measured with a digital camera in 83 children in a German subsample of the IDEFICS study. Among those 56 children performed a taste threshold test for bitter and taste preference tests for sweet, salty, fatty and umami. The association between the number of FP and sensory taste perception was analysed. Results: There is a tendency towards a lower number of FP in children with a higher fat preference (30 vs. 25 papillae, p=0.06). Results show no association between the number of FP and neither the bitter taste thresholds nor taste preferences for sweet, salty and umami. Conclusion: Bitter taste threshold might be independent of the number of FP, while the perception of fat was associated with the number of FP.
| S-EPMC5533126 | biostudies-other
Project description:Surface orientation is an important visual primitive that can be estimated from monocular or binocular (stereoscopic) signals. Changes in motor planning occur within about 200 ms after either type of signal is perturbed, but the time it takes for apparent (perceived) slant to develop from stereoscopic cues is not known. Apparent slant sometimes develops very slowly (Gillam, Chambers, & Russo, 1988; van Ee & Erkelens, 1996). However, these long durations could reflect the time it takes for the visual system to resolve conflicts between slant cues that inevitably specify different slants in laboratory displays (Allison & Howard, 2000). We used a speed-accuracy tradeoff analysis to measure the time it takes to discriminate slant, allowing us to report psychometric functions as a function of response time. Observers reported which side of a slanted surface was farther, with a temporal deadline for responding that varied block-to-block. Stereoscopic slant discrimination rose above chance starting at 200 ms after stimulus onset. Unexpectedly, observers discriminated slant from binocular disparity faster than texture, and for stereoscopic whole-field stimuli faster than stereoscopic slant contrast stimuli. However, performance after the initial deviation from chance increased more rapidly for slant-contrast stimuli than whole-field stimuli. Discrimination latencies were similar for slants about the horizontal and vertical axes, but performance increased faster for slants about the vertical axis. Finally, slant from vertical disparity was somewhat slower than slant from horizontal disparity, which may reflect cue conflict. These results demonstrate, in contradiction with the previous literature, that the perception of slant from disparity happens very quickly-in fact, more quickly than the perception of slant from texture-and in comparable time to the simple perception of brightness from luminance.
| S-EPMC5713489 | biostudies-literature
Project description:A novel delivery method is described that incorporates taste stimuli into edible strips for determining n-propylthiouracil (PROP) taster status. Edible strips that contained 400 or 600 nanomoles of PROP were prepared for psychophysical studies. Using these strips, we measured taste intensity, taste hedonics, and taste quality responses in a sample of healthy volunteers (n = 118). Participants were also asked to assess a single NaCl strip, a quinine strip, 3 NaCl solutions, and 3 PROP solutions. All psychophysical data were subsequently analyzed as a function of TAS2R38 genotype. The use of PROP strips for distinguishing between individuals with at least 1 PAV allele and individuals with other genotypes was assessed and compared with the use of PROP solutions for making this same distinction. For the 2 PROP strips and PROP solutions, individuals who expressed at least 1 PAV allele could perceive the bitter taste of PROP. Individuals who expressed 2 AVI alleles responded similarly to 400 nanomole PROP strips and blank strips. Furthermore, individuals with 2 AVI alleles responded to 0.032 and 0.32 mM PROP solutions at intensities that were similar to water, though intensity ratings to 3.2 mM PROP solution exceeded water. In general, those with at least 1 PAV allele rated the bitter taste of PROP as unpleasant in both delivery methods (strips or solutions). Psychophysical data from PROP strips and solutions were consistent with TAS2R38 genotype. These results support the validity of edible taste strips as a method for assessing PROP taste perception in humans.
| S-EPMC3685426 | biostudies-literature
Project description:Determination of the number of fungiform papillae (FP) on the human tongue is an important measure that has frequently been associated with individual differences in oral perception, including taste sensitivity. At present, there is no standardised method consistently used to identify the number of FP, and primarily scientists manually count papillae over a small region(s) of the anterior tip of a stained tongue. In this study, a rapid automated method was developed to quantify the number of FP across the anterior 2cm of an unstained tongue from high resolution digital images. In 60 participants, the automated method was validated against traditional manual counting, and then used to assess the relationship between the number of FP and taste phenotype (both 6-n-propylthiouracil (PROP) and Thermal Taster Status). FP count on the anterior 2cm of the tongue was found to correlate significantly with PROP taster status. PROP supertasters (PSTs) had a significantly higher FP count compared with PROP non-tasters (PNTs). Conversely, the common approach used to determine the number of FP in a small 6mm diameter circle on the anterior tongue tip, did not show a significant correlation irrespective of whether it was determined via automated or manual counting. The regional distribution of FP was assessed across PROP taster status groups. PSTs had a significantly higher FP count within the first centimetre of the anterior tongue compared with the PNT and PROP medium-tasters (PMT), with no significant difference in the second centimetre. No significant relationship was found with Thermal Taster Status and FP count, or interaction with PROP taster status groups, supporting previous evidence suggesting these phenomena are independent. The automated method is a valuable tool, enabling reliable quantification of FP over the anterior 2cm surface of the tongue, and overcomes subjective discrepancies in manual counting.
| S-EPMC5766753 | biostudies-literature
Project description:It is well known that nutritional intake can vary substantially as a function of demographic variables such as ethnicity and/or sex. Although a variety of factors are known to underlie the relationship between these demographic variables and nutritional intake, it is interesting to speculate that variation in food intake associated with ethnicity or sex may result, in part, from differences in the perceived taste of foods in these different populations. Thus, we initiated a study to evaluate taste responsiveness in different ethnic groups. Moreover, because of the known differences in taste responsiveness between males and females, analyses were stratified by sex. The ethnic groups tested differed significantly from one another in reported perceived taste intensity. Our results showed that Hispanics and African Americans rated taste sensations higher than non-Hispanic Whites and that these differences were more pronounced in males. Understanding the nature of these differences in taste perception is important, because taste perception may contribute to dietary health risk. When attempting to modify diet, individuals of different ethnicities may require personalized interventions that take into account the different sensory experience that these individuals may have when consuming foods.
| S-EPMC4910674 | biostudies-literature
Project description:BACKGROUND:The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli. METHODS AND FINDINGS:Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs) 1a, 1beta, 2a, 2b, and 3; and polycystic kidney disease (PKD) channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-beta2, the delta-subunit of epithelial sodium channel (ENaC) and the bitter receptor T2R14, as well as beta-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1beta, PKD2L1, phospholipase C-beta2, and delta-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells. CONCLUSIONS:These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals ("natural knockouts") suggests a cell lineage for sour that is independent of the other taste modalities.
| S-EPMC2754526 | biostudies-literature
Project description:Kokumi taste is a well-accepted and characterised taste modality and is described as a sensation of enhancement of sweet, salty, and umami tastes. The Calcium Sensing Receptor (CaSR) has been designated as the putative kokumi taste receptor for humans, and a number of kokumi-active ligands of CaSR have been discovered recently with activity confirmed both in vivo and in vitro. Domestic cats (Felis catus) are obligate carnivores and accordingly, their diet is abundant in proteins, peptides, and amino acids. We hypothesised that CaSR is a key taste receptor for carnivores, due to its role in the detection of different peptides and amino acids in other species. Using in silico, in vitro and in vivo approaches, here we compare human CaSR to that of a model carnivore, the domestic cat. We found broad similarities in ligand specificity, but differences in taste sensitivity between the two species. Indeed our in vivo data shows that cats are sensitive to CaCl2 as a kokumi compound, but don't show this same activity with Glutathione, whereas for humans the reverse is true. Collectively, our data suggest that kokumi is an important taste modality for carnivores that drives the palatability of meat-derived compounds such as amino acids and peptides, and that there are differences in the perception of kokumi taste between carnivores and omnivores.
| S-EPMC8131363 | biostudies-literature