Forced-choice Staircase Research Articles

Perceptual thresholds for differences in CT noise texture.

The average () or peak () noise power spectrum (NPS) frequency is often used as a one-parameter descriptor of the CT noise texture. Our study develops a more complete two-parameter model of the CT NPS and investigates the sensitivity of human observers to changes in it. A model of CT NPS was created based on its and a half-Gaussian fit () to the downslope. Two-alternative forced-choice staircase studies were used to determine perceptual thresholds for noise texture, defined as parameter differences with a predetermined level of discrimination performance (80% correct). Five imaging scientist observers performed the forced-choice studies for eight directions in the -space, for two reference NPSs (corresponding to body and lung kernels). The experiment was repeated with 32 radiologists, each evaluating a single direction in the -space. NPS differences were quantified by the noise texture contrast (), the integral of the absolute NPS difference. The two-parameter NPS model was found to be a good representation of various clinical CT reconstructions. Perception thresholds for alone are for body and for lung NPSs. For , these values are 0.15 and , respectively. Thresholds change if the other parameter also changes. Different NPSs with the same or can be discriminated. Nonradiologist observers did not need more than radiologists. or is insufficient to describe noise texture completely. The discrimination of noise texture changes depending on its frequency content. Radiologists do not discriminate noise texture changes better than nonradiologists.

Disgust sensitivity relates to affective responses to – but not ability to detect – olfactory cues to pathogens

Hundreds of studies have assessed variation in the degree to which people experience disgust toward substances associated with pathogens, but little is known about the mechanistic sources of this variation. The current investigation uses olfactory perception and threshold methods to test whether it is apparent at the cue-detection level, at the cue-interpretation level, or both. It further tests whether relations between disgust sensitivity and olfactory perception are specific to odors associated with pathogens. Two studies (N's = 119 and 160) of individuals sampled from a Dutch university each revealed that pathogen disgust sensitivity relates to valence perceptions of odors found in pathogen sources, but not to valence perceptions of odors not associated with pathogens, nor to intensity perceptions of odors of either type. Study 2, which also assessed olfactory thresholds via a three-alternative forced-choice staircase method, did not reveal a relation between pathogen disgust sensitivity and the ability to detect an odor associated with pathogens, nor an odor not associated with pathogens. In total, results are consistent with the idea that pathogen disgust sensitivity relates to how olfactory pathogen cues are interpreted after detection, but not necessarily to the ability to detect such cues.

Assessing tactile acuity in oral tissues: Challenges of stimulus development

The human oral cavity is comprised of a variety of mechanosensitive structures likely involved in food texture perception. However, studies evaluating oral tactile acuity are often limited to the tongue, which may miss relevant contributions coming from other oral tissues. To address this knowledge gap, the relative acuities of three oral soft tissues, the tongue, the hard palate, and the gums, were assessed in adults (n = 90) using the forced-choice staircase technique. It was hypothesized the tongue would show superior acuity over the more keratinized surfaces due to its flexible nature and thinner epidermis, while the palate would be superior to the gums due to the palate’s high density of mechanoreceptive endings. Discrimination acuities for the tissues were assessed using three different sets of stimuli previously adapted for use on the tongue, punctate-pressure (F; 0.0044–0.010 g), edge-sharpness (∡; 90.0–135.0°), and surface roughness (Ra; 0.177–0.465 μm), via a just-noticeable-difference (JND) task. Participants were found to have significantly lower JNDs with their tongues for all percepts tested (p ≤ 0.019, all), while discrimination thresholds on the palate were only significantly lower than those seen on the gums in the roughness assessment condition (p = 0.013). Both the gums and palate, however, showed similar acuity to previously obtained sensitivity values for the fingertip for all tested percepts. These findings do suggest that all tissues are highly sensitive and likely critical for texture perception, but the lack of significant difference between the palate and gums may also be partially attributable to the stimuli being ill-suited for use in palate assessments. While all stimuli used were well-suited for use in lingual evaluations, the palate’s curved geometry and limited accessibility made application and evaluation of both the punctate-pressure and edge sharpness stimuli challenging. Further adaptation of stimuli to optimize them for use on more-rigid tissues could provide further insight into the relative acuity of these different tissues.

Human Oral Sensitivity to and Taste Modulation by 3-Mercapto-2-Methylpentan-1-ol.

Introduction3-Mercapto-2-methylpentan-1-ol (3 M) is a key onion flavor (aroma), but past sensory work has focused primarily on ortho-nasal presentation. A series of experiments was conducted to characterize human sensitivity to oral 3 M solutions, then determine how 3 M impacts perception of basic tastes.MethodsDetection thresholds were measured for a food grade, racemic mixture using a forced-choice staircase procedure (n = 19). Recognition was measured by presenting a single stimulus per trial (3 M, vanillin, or water), with “onion,” “vanilla,” or “water” as responses (n = 18). Supra-threshold intensity (n = 20) was measured for various concentrations using the general labeled magnitude scale (gLMS). Odor-taste interactions were studied using mixtures of 3 M and exemplars of basic tastes. Participants rated the intensity of basic tastes, or both taste and aroma, using the gLMS (n ranged from 10 to 15). All stimuli were in aqueous solution.ResultsParticipants detected oral 3 M at about 0.90 ppb and recognized 3 M as “onion” at about 5 ppb. Supra-threshold intensity increased roughly as a cumulative logistic function of concentration. 3 M enhanced the rated savory intensity of monosodium glutamate, but did not enhance the dominant qualities of exemplars of the other four basic tastes. Under a response-context more favorable to an analytic approach, savory enhancement was reduced but not eliminated. Savory enhancement was eliminated with nose-clips.ConclusionsOral sensitivity was lower than previous retronasal studies would suggest, but roughly consistent with concentrations in cooked allium varieties. Oral 3 M selectively enhanced savory intensity, an effect likely due to retronasal aroma rather than taste or mouthfeel.Implication3 M is a promising candidate aroma to enhance or impart a savory flavor.

Elucidation of a lingual detection mechanism for high-viscosity solutions in humans.

While perception of high-viscosity solutions (η > 1000 cP) is speculated to be linked to filiform papillae deformation, this has not been demonstrated psychophysically. Presently, just-noticeable-viscosity-difference thresholds were determined using the forced-choice staircase method and high-viscosity solutions (η = 4798-12260 cP) with the hypotheses that the tongue would be chiefly responsible for viscosity perception in the oral cavity, and that individuals with more, longer, narrower filiform papillae would show a greater acuity for viscosity perception. Subjects (n = 59) evaluated solutions in a normal, "unblocked" condition as well as in a "palate blocked" condition which isolated the tongue so that only perceptual mechanisms on the lingual tissue were engaged. Optical profiling was used to characterize papillary length, diameter, and density in tongue biopsies of a subset (n = 45) of participants. Finally, psychophysical and anatomical data were used to generate a novel model of the tongue surface as porous media to predict papillary deformation as a strain-detector for viscosity perception. Results suggest that viscosity thresholds are governed by filiform papillae features. Indeed, anatomical characterization of filiform papillae suggests sensitivity to high-viscosity solutions is associated with filiform papillae length and density (r = 0.68, p < 0.00001), but not with diameter. Modelling indicated this is likely due to a reciprocal interaction between papillae diameter and fluid shear stress. Papillae with larger diameters would result in higher viscous shear stress due to a narrower gap and stronger fluid-structure interaction, but a larger-diameter papilla would also deform less easily.

Umami detection threshold among children of different ethnicities and its correlation with various indices of obesity and blood pressure

Sensitivity to savory taste has been linked to high consumption of savory foods and increased risks of obesity and hypertension. However, there are limited studies that investigate whether obesity indices are correlated with the differences in umami taste perception, particularly in children. This study aimed to investigate the umami detection threshold among children of different ethnicities and the threshold's correlation with obesity indices and blood pressure. A total of 140 subjects were recruited and consisted of a nearly equal distribution of children from three main ethnicities (37.2% Malays, 31.4% Chinese, 31.4% Indians). Umami detection threshold was measured using the two-alternative, forced-choice staircase procedure. Body weight, height, waist circumference and blood pressure of children were measured. Body composition was assessed using bioelectrical impedance analysis (BIA). Mean umami detection threshold was 1.22 ± 1.04 mM and there were no observable differences attributable to the subjects' ethnicities. Body fat percentage was negatively correlated (r = −0.171, p < 0.05), while lean body mass percentage was positively correlated (r = 0.171, p < 0.05) with umami detection threshold. These findings revealed that umami taste perception correlated with children's body composition, but not other anthropometric indicators and blood pressure. Future studies should explore the correlation between umami taste perception and children's total dietary intake.

Are Spatial Chromatic Contrast Sensitivity Band-pass or Lowpass Functions?

The goal of this research is to generate high quality chromatic Contrast Sensitivity Function (CSF) over a wide range of spatial frequencies from 0.06 to 3.84 cycles per degree (cpd) surrounding 5 CIE proposed colour centres (white, red, yellow, green and blue) to study colour difference. At each centre, 6 colour directions at each of 7 frequencies were sampled, from 0.06 to 3.84 cycles per degree (cpd) corresponding to the number of cycles: from 2.3 to 144.4 respectively. A threshold method based on forced-choice stair-case was adopted to investigate the just noticeable (threshold) colour difference. The results revealed that the chromatic CSF under the present experimental conditions having many lower spatial frequencies covering five colour centres to be band pass, whereas previous results indicated it was low pass. However, this could be caused by the present experimental conditions such as fixed-size stimuli and constant luminance. The new chromatic CSF for R-G and Y-B channels were also developed.

Taste detection threshold of human (Homo sapiens) subjects and taste preference threshold of black-handed spider monkeys (Ateles geoffroyi) for the sugar substitute isomalt

The artificial sweetener isomalt is widely used due to its low caloric, non-diabetogenic and non-cariogenic properties. Although the sweetening potency of isomalt has been reported to be lower than that of sucrose, no data on the sensitivity of humans for this polyol are available. Using an up-down, two-alternative forced choice staircase procedure we therefore determined taste detection thresholds for isomalt in human subjects (n = 10; five females and five males) and compared them to taste preference thresholds, determined using a two-bottle preference test of short duration, in a highly frugivorous nonhuman primate, the spider monkey (n = 4; one female, three males). We found that both species detected concentrations of isomalt as low as 20 mM. Both humans and spider monkeys are less sensitive to isomalt than to sucrose, which is consistent with the notion of the former being a low-potency sweetener. The spider monkeys clearly preferred all suprathreshold concentrations tested over water, suggesting that, similar to humans, they perceive isomalt as having a purely sweet taste that is indistinguishable from that of sucrose. As isomalt, like most sweet-tasting polyols, may elicit gastric distress when consumed in large quantities, the present findings may contribute to the choice of appropriate amounts and concentrations of this sweetener when it is employed as a sugar substitute or food additive for human consumption. Similarly, the taste preference threshold values of spider monkeys for isomalt reported here may be useful for determining how much of it should be used when it is employed as a low-caloric sweetener for frugivorous primates kept on a vegetable-based diet, or when medication needs to be administered orally.

Temporal frequency discrimination in amblyopia.

The present study aimed to explore temporal frequency discrimination in amblyopia, and the influence of attentional load on amblyopic temporal cognition. Twenty anisometropic amblyopes, 20 strabismic amblyopes and 20 normal subjects were recruited. A flickering disk was used for visual stimuli. A two-alternative, forced-choice staircase paradigm was used to measure the temporal frequency discrimination thresholds of amblyopic eyes, fellow eyes and normal dominant eyes under reference temporal frequencies of 5, 10 and 20 Hz. The just-noticeable differences data were analyzed statistically. In addition, the temporal frequency discrimination thresholds of the subjects were measured under different conditions of attentional load. The changes in temporal frequency discrimination thresholds were compared between amblyopic and normal eyes when attention was loaded. At the reference temporal frequencies of 5 and 10 Hz, temporal thresholds of amblyopic eyes were significantly increased compared with fellow eyes (P<0.05). Regarding strabismic amblyopia, temporal thresholds of fellow eyes were increased compared with normal eyes (P<0.05). However, no correlation was identified between the temporal-frequency discrimination thresholds and the LogMAR visual acuities in amblyopic eyes. In addition, higher attentional load caused greater changes in temporal thresholds in amblyopic eyes, but the situation was not the same for lower attentional load. In conclusion, in the present study a deficit of temporal frequency discrimination in amblyopic eyes and the fellow eyes of strabismic amblyopes was identified. Furthermore, the influence of attentional load on temporal frequency discrimination in amblyopic eyes was increased compared with normal eyes.

Visual Acuity and Contrast Sensitivity Development in Children: Sweep Visually Evoked Potential and Psychophysics

The purpose of this study was to investigate the development of visual acuity (VA) and contrast sensitivity in children as measured with objective (sweep visually evoked potential) and subjective, psychophysical techniques, including signal detection theory (SDT), which attempts to control for differences in criterion or behavior between adults and children. Furthermore, this study examines the possibility of applying SDT methods with children. Visual acuity and contrast thresholds were measured in 12 children 6 to 7 years old, 10 children 8 to 9 years old, 10 children 10 to 12 years old, and 16 adults. For sweep visually evoked potential measurements, spatial frequency was swept from 1 to 40 cpd to measure VA, and contrast of sine-wave gratings (1 or 8 cpd) was swept from 0.33 to 30% to measure contrast thresholds. For psychophysical measurements, VA and contrast thresholds (1 or 8 cpd) were measured using a temporal two-alternative forced-choice staircase procedure and also with a yes-no SDT procedure. Optotype (logMAR [log of the minimum angle of resolution]) VA was also measured. The results of the various procedures were in agreement showing that there are age-related changes in threshold values and logMAR VA after the age of 6 years and that these visual functions do not become adult-like until the age of 8 to 9 years at the earliest. It was also found that children can participate in SDT procedures and do show differences in criterion compared with adults in psychophysical testing. These findings confirm a slightly later development of VA and contrast sensitivity (8 years or older) and indicate the importance of using SDT or forced-choice procedures in any developmental study to attempt to overcome the effect of criterion in children.

Simulation model for interaural time difference discrimination for tones

Difference limens for the interaural time difference (ITD) can be measured with a 2-interval, 2-alternative forced-choice staircase using the ITD as the staircase variable. Experimental results can be predicted by a computational model that simulates the experiment protocol in every important detail, as applied to human listeners, but the computer can tolerate hundreds of times more runs. At the core of the simulation is a decision process based on an opponency model for the two medial superior olives (MSO). MSO firing rates as functions of ITD are initially determined by a stochastically driven Hodgkin-Huxley cell model and represented in the simulation by a four-parameter fitted function. A corresponding noise function is estimated from multiple runs of the cell model. Left-right symmetry in both the model and the experiment protocol simplifies the calculations. Simulations have practical value in relating staircase thresholds to the underlying parameterized firing rate functions for given staircase var...

Attitudes about race predict individual differences in face adaptation aftereffects

This study examined whether category boundaries between Black and White faces relate to individual attitudes about race. Fifty-seven (20 Black, 37 White) participants completed measures of explicit racism, implicit racism, collective self-esteem (CSE), and racial centrality. Category boundaries between Black and White faces were measured in three separate conditions: following adaptation to (1) a neutral gray background, a sequence of (2) Black or (3) White faces. Two additional conditions measured category boundaries for facial distortion to investigate whether attitudes relate to mechanisms of racial identity alone, or to more global mechanisms of face perception. Using a two-alternative forced-choice staircase procedure, participants indicated whether a test image appeared to be Black or White (or contracted or expanded). Following neutral adaptation, participants with higher CSE showed category boundaries shifted toward faces with a higher percentage of Black features. In addition, the strength of short-term sensitivity shifts following adaptation to Black and White faces was related to explicit and implicit attitudes about race. Sensitivity shifts were weaker when participants scored higher on explicit racism, but were stronger when participants scored higher on implicit but lower on explicit racism. The results of this study indicate that attitudes about race account for some individual differences in natural category boundaries between races as well as the strength of identity aftereffects following face adaptation.

Point pressure sensitivity in early stage Parkinson's disease

A number of sensory changes occur in the earliest stages of Parkinson's disease (PD), some of which precede the expression of the classic motor phenotype by years (e.g., olfactory dysfunction). Whether point pressure sensitivity (PPS), a cutaneous measure of light touch mediated by myelinated Aβ fibers, is altered in early PD is not clear. Prior studies on this point are contradictory and are based on non-forced-choice threshold tests that confound the sensitivity measure with the response criterion. While α-synuclein pathology, a defining feature of PD, is present in the skin of PD patients, it is restricted to unmyelinated nerve fibers, suggesting PPS may be spared in this disease. We determined PPS thresholds using a state-of-the-art forced-choice staircase threshold test paradigm in 29 early stage PD patients and 29 matched controls at 11 body sites: the center of the forehead and the left and right forearms, index fingers, palms, medial soles of the feet, and plantar halluces. The patients were tested, in counterbalanced sessions, both on and off dopamine-related medications (DRMs). PPS was not influenced by PD and did not correlate with DRM l-DOPA equivalents, scores on the Unified Parkinson's Disease Rating Scale, side of the major motor disturbances, or SPECT imaging of the striatal dopamine transporter, as measured by technetium-99m TRODAT. However, PPS thresholds were lower on the left than on the right side of the body (p=0.008) and on the upper extremities relative to the toes and feet (ps<0.0001). Positive correlations were evident among the thresholds obtained across all body sectors, even though disparate regions of the body differed in terms of absolute sensitivity. This study indicates that PPS is not influenced in early stage PD regardless of whether patients are on or off DRMs.

The effect of implied motion on the motion after-effect

Directional motion adaptation has previously been reported following exposure to sequences of unrelated still photographs depicting implied motion (‘implied motion after-effect’, IMAE; Winawer et al., 2008). To investigate the relationship between processes activated by implied motion and by explicit dynamic motion, we tested whether the IMAE can combine with the classical motion after-effect (CMAE) elicited by adaptation to drifting dot patterns. Participants adapted to stimuli which combined moving dot patterns with sequences of static implied-motion images. Motion adaptation was measured using a forced-choice staircase procedure in which the displacement of drifting test dots was varied to find the observer’s motion ‘null’ point. Following adaptation to combinations of still images and incoherently moving dots, the null point shifted by a small amount in the direction predicted by earlier IMAE reports. Adaptation to combinations of still images and coherently moving dots also affected the magnitude of the CMAE, consistent with a modulatory effect of implied motion on directional adaptation. These psychophysical results indicate that implied motion can influence adaptation in motion selective processes, but the underlying mechanism remains to be established.

Individual Differences in Sour and Salt Sensitivity: Detection and Quality Recognition Thresholds for Citric Acid and Sodium Chloride

Taste sensitivity is assessed with various techniques, including absolute detection and quality recognition. For any stimulus, one might expect individual differences in sensitivity to be reflected in all measures, but they are often surprisingly independent. Here, we focus on sensitivity to sour and salty taste, in part because processing of these qualities is poorly understood relative to other tastes. In Study 1, we measured retest reliability for detection (modified, forced-choice staircase method) and recognition (modified Harris-Kalmus procedure) for both citric acid (CA) and sodium chloride (NaCl). Despite good retest reliability, individual differences in detection and recognition were weakly correlated, suggesting that detection and recognition of sour and salty stimuli may reflect different physiological processes. In Study 2, a subset of subjects returned to contribute full detection (psychometric) functions for CA and NaCl. Thresholds estimated from full detection functions correlated with both staircase and recognition thresholds, suggesting that both tasks may reflect absolute sensitivity to some extent. However, the ranges of individual differences were systematically compressed for staircase thresholds relative to those from full detection functions. Thus, individual differences in sensitivity appear to interact with different test methodologies in lawful ways. More work will be required to understand how different taste phenotypes relate to one another.

Genetic Variation in Putative Salt Taste Receptors and Salt Taste Perception in Humans

The objective of this study was to determine whether single nucleotide polymorphisms (SNPs) in the SCNN1A (3), SCNN1B (12), SCNN1G (6), and TRPV1 (10) genes affect salt taste perception. Participants were men (n = 28) and women (n = 67) from the Toronto Nutrigenomics and Health study aged 21-31 years. Taste thresholds were determined using a 3-alternative forced-choice staircase model with solutions ranging from 9×10(-6) to 0.5 mol/L. Suprathreshold taste sensitivity to 0.01-1.0 mol/L salt solutions was assessed using general labeled magnitude scales. None of the SNPs in the SCNN1A and SCNN1G genes were significantly associated with either outcome. In the SCNN1B gene, 2 SNPs in intronic regions of the gene modified suprathreshold taste sensitivity (mean iAUC ± SE). Those homozygous for the A allele of the rs239345 (A>T) polymorphism and the T allele of the rs3785368 (C>T) polymorphism perceived salt solutions less intensely than carriers of the T or C alleles, respectively (rs239345: 70.82±12.16 vs. 96.95±3.75, P = 0.02; rs3785368: 57.43±19.85 vs. 95.57±3.66, P = 0.03) In the TRPV1 gene, the rs8065080 (C>T, Val585Ile) polymorphism modified suprathreshold taste sensitivity where carriers of the T allele were significantly more sensitive to salt solutions than the CC genotype (98.3±3.8 vs. 74.1±8.3, P = 0.008). Our findings show that variation in the TRPV1 and the SCNN1B genes may modify salt taste perception in humans.

Reproducibility of the measurement of sweet taste preferences

Developing interventions to prevent and treat obesity are medical and public health imperatives. Taste is a major determinant of food intake and reliable methods to measure taste preferences need to be established. This study aimed to establish the short-term reproducibility of sweet taste preference measurements using 5-level sucrose concentrations in healthy adult volunteers. We defined sweet taste preference as the geometric mean of the preferred sucrose concentration determined from two series of two-alternative, forced-choice staircase procedures administered 10min apart on a single day. We repeated the same procedures at a second visit 3–7days later. Twenty-six adults (13 men and 13 women, age 33.2±12.2years) completed the measurements. The median number of pairs presented for each series was three (25th and 75th percentiles: 3, 4). The intraclass correlation coefficients between the measurements was 0.82 (95% confidence interval [CI]: 0.63–0.92) within a few days. This study showed high short-term reproducibility of a simple, 5-level procedure for measuring sweet taste preferences. This method may be useful for assessing sweet taste preferences and the risks resulting from those preferences.

Effects of contrast on spatial and temporal integration in 2D shape perception from dynamic occlusion

In self-motion, research has shown that optic flow can be a source that supplies essential information about heading, speed, and characteristics of the surrounding environment. Evidence has shown that increases in optic flow quality and quantity have additive effects on steering performance. Further, studies have shown that spatial integration (e.g., stimuli density) and temporal integration (e.g., stimuli lifetime) may play a key role in motion perception. In the current study, we examined how spatial and temporal integration are affected by the quality of optic flow in generating 2-D shape perception. Participants were asked to identify a 2D shape resulting from kinetic occlusion information. Displays consisted of 2D arrays of dots forming both foreground objects and the background texture. When the foreground object moves the disappearance and reappearance of back ground dots can be used to recover the object shape. Three experiments were conducted in which optic flow density, display contrast, and optic flow lifetime were variables of interest. In each of the three experiments, the threshold of one variable was measured, using a four-alternative forced choice staircase, while the other two variables were manipulated. In experiment 1, optical flow density threshold was measured for 8 participants using a 2 (contrast) by 2 (lifetime) within-subjects design; in experiment 2, contrast threshold was measured for 5 participants using a 3 (density) by 3 (lifetime) within-subjects design; in experiment 3, lifetime threshold was measured for 5 participants using a 3 (density) by 3 (contrast) within-subjects design. The results showed the performance in 2D shape perception decreased as a function of decreased contrast, decreased lifetime, and decreased density. These results suggest the spatial and temporal integration might be potential predictors of driving performance under low contrast conditions. Meeting abstract presented at VSS 2012

Genetic variation in the epithelial sodium channel (ENaC) and salt taste perception in humans

Despite individual differences in salt taste sensitivity no studies have identified variations in genes that explain this variability. Our objective was to determine whether single nucleotide polymorphisms (SNPs) in the epithelial sodium channel (ENaC), a putative salt taste receptor with 3 subunits, modifies salt (NaCl) taste in men (n=28) and women (n=67) aged 20–35 yrs. Taste thresholds (TT) were determined using a 3 alternative forced choice staircase model with solutions ranging from 9 ×10−6 to 0.5 mol/L. Suprathreshold taste sensitivity (STT) to 5 solutions (0.01–1 mol/L) was assessed using a general Labeled Magnitude Scale. Genotypes were extracted from an Affymetrix 6.0 chip (5 SNPs in SCNN1A; 34 SNPs in SCNN1B; 13 SNPs in SCNN1G). A general linear model was used to compute differences between genotypes. No SNPs in the SCNN1A or SCNN1G genes modified salt taste. In the SCNN1B gene the rs9939129 (C&gt;T) SNP modified TT (mmol/L ± SE) where carriers of the T allele detected significantly lower NaCl concentrations than CC homozygotes (2.33±0.76 vs 3.85±0.37, p=0.02). The rs239345 (A&gt;T) SNP in this gene modified STT (iAUC ± SE) were those homozygous for the A allele perceived salt solutions less intensely than carriers of the T allele (70.82±12.16 vs. 96.95±3.75, p=0.02). Our findings indicate that variation in the SCNN1B gene modifies salt taste perception in humans.Grant Funding Source : The Advanced Food and Materials Network

Genetic variation in TAS1R2 taste receptor and sweet taste perception and sugar intake

Taste is one of the primary determinants of food intake and variation in genes affecting taste pathways may influence taste perception and food intake. The TAS1R2 protein is part of the putative TAS1R2/TAS1R3 sweet taste receptor and likely plays a primary role in detecting sugars. Our objective was to determine whether single nucleotide polymorphisms (SNPs) in the TAS1R2 gene affect sweet (sucrose) taste (n = 95) and intake of sugars (n=535). Sucrose taste thresholds were determined using a 3 alternative forced choice staircase model with solutions ranging from 9 ×10−6 to 0.5 mol/L. Genotypes for 23 SNPs in the TAS1R2 gene were extracted from an Affymetrix 6.0 chip. Sucrose and total sugar intake was calculated using a 196 item semi‐quantitative food frequency questionnaire. A general linear model was used to compute differences between genotypes. The rs12075191 (A&gt;G) SNP was associated with sucrose taste and intake. Carriers of the A allele had lower taste thresholds (7.00 ± 1.65 vs 9.27 ± 0.63 mmol/L, p=0.058), lower total sugar intake (111.2 ± 7.3 vs 125.9 ± 2.4 grams, p = 0.05) and lower sucrose intake(41.1 ± 3.4 vs 48.7 ± 1.1 grams, p=0.03) than TT homozygotes. These results show that the rs12075191 SNP in the TAS1R2 gene modifies both sweet taste perception and sugar intake.Grant Funding Source : The Advanced Food and Materials Network