Dr. Joseph is supported by National Institute of Alcohol Abuse and Alcoholism (Z01AA000135) and National Institute of Nursing Research (NINR) (1ZNR0000035-01) and NIH Distinguished Scholar funds; Dr. Mennella is supported by the National Institutes of Deafness and Other Communication Disorders (NIDCD) grants DC016616 and DC011287; Dr. Cowart&#39;s effort in refining the TDT test was supported by NIDCD grant P50 DC000214; and Dr. Pepino is supported by American Diabetes Association (ADA) grant 1-19-ICTS-092 and by the USDA National Institute of Food and Agriculture (NIFA) Hatch Project 698-921. The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH, NINR, NIDCD, ADA, or USDA NIFA. The funding agencies had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation or contents of the manuscript.

<ol>
	<li>Bartoshuk, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+psychophysics+of+taste.">The psychophysics of taste.</a> The American Journal of Clinical Nutrition. 31 (6), 1068-1077 (1978).</li><li>Pribitkin, E., Rosenthal, M. D., Cowart, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+and+causes+of+severe+taste+loss+in+a+chemosensory+clinic+population.">Prevalence and causes of severe taste loss in a chemosensory clinic population.</a> Annals of Otology, Rhinology, and Laryngology. 112 (11), 971-978 (2003).</li><li>Kouzuki, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+and+recognition+thresholds+for+five+basic+tastes+in+patients+with+mild+cognitive+impairment+and+Alzheimer's+disease+dementia.">Detection and recognition thresholds for five basic tastes in patients with mild cognitive impairment and Alzheimer's disease dementia.</a> BMC Neurology. 20 (1), 110 (2020).</li><li>Joseph, P. V., Reed, D. R., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Individual+differences+among+children+in+sucrose+detection+thresholds:+Relationship+with+age,+gender,+and+bitter+taste+genotype.">Individual differences among children in sucrose detection thresholds: Relationship with age, gender, and bitter taste genotype.</a> Nursing Research. 65 (1), 3-12 (2016).</li><li>Nance, K., Acevedo, M. B., Pepino, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+taste+function+and+ingestive+behavior+following+bariatric+surgery.">Changes in taste function and ingestive behavior following bariatric surgery.</a> Appetite. 146, 104423 (2020).</li><li>Bobowski, N., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repeated+exposure+to+low-sodium+cereal+affects+acceptance+but+does+not+shift+taste+preferences+or+detection+thresholds+of+children+in+a+randomized+clinical+trial.">Repeated exposure to low-sodium cereal affects acceptance but does not shift taste preferences or detection thresholds of children in a randomized clinical trial.</a> Journal of Nutrition. 149 (5), 870-876 (2019).</li><li>Bobowski, N. K., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+in+the+relationship+between+blood+pressure+and+salty+taste+thresholds+among+overweight+and+obese+children.">Disruption in the relationship between blood pressure and salty taste thresholds among overweight and obese children.</a> Journal of the Academy of Nutrition and Dietetics. 115 (8), 1272-1282 (2015).</li><li>Petty, S., Salame, C., Mennella, J. A., Pepino, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+between+sucrose+taste+detection+thresholds+and+preferences+in+children,+adolescents,+and+adults.">Relationship between sucrose taste detection thresholds and preferences in children, adolescents, and adults.</a> Nutrients. 12 (7), 1918 (2020).</li><li>Pepino, M. Y., Finkbeiner, S., Beauchamp, G. K., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obese+women+have+lower+monosodium+glutamate+taste+sensitivity+and+prefer+higher+concentrations+than+do+normal-weight+women.">Obese women have lower monosodium glutamate taste sensitivity and prefer higher concentrations than do normal-weight women.</a> Obesity (Silver Spring). 18 (5), 959-965 (2010).</li><li>Pepino, M. Y., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+cigarette+smoking+and+family+history+of+alcoholism+on+sweet+taste+perception+and+food+cravings+in+women.">Effects of cigarette smoking and family history of alcoholism on sweet taste perception and food cravings in women.</a> Alcoholism: Clinical and Experimental Research. 31 (11), 1891-1899 (2007).</li><li>Cowart, B. J., Yokomukai, Y., Beauchamp, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bitter+taste+in+aging:+compound-specific+decline+in+sensitivity.">Bitter taste in aging: compound-specific decline in sensitivity.</a> Physiology &amp; Behavior. 56 (6), 1237-1241 (1994).</li><li>Hoehl, K., Schoenberger, G. U., Busch-Stockfisch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+quality+and+taste+sensitivity+for+basic+tastes+and+metallic+sensation.">Water quality and taste sensitivity for basic tastes and metallic sensation.</a> Food Quality and Preference. 21, 243-249 (2010).</li><li>Wetherill, G. B., Levitt, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequential+estimation+of+points+on+a+psychometric+function.">Sequential estimation of points on a psychometric function.</a> British Journal of Mathematical and Statistical Psychology. 18, 1-10 (1965).</li><li>Chambers, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commentary:+conducting+sensory+research+in+children.">Commentary: conducting sensory research in children.</a> Journal of Sensory Studies. 20 (1), 90-92 (2005).</li><li>Mennella, J. A., Bobowski, N. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Psychophysical+tracking+method+to+measure+taste+preferences+in+children+and+adults.">Psychophysical tracking method to measure taste preferences in children and adults.</a> Journal of Visualized Experiments: JoVE. , e35416 (2016).</li><li>Running, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+false+positive+rates+in+common+sensory+threshold+tests.">High false positive rates in common sensory threshold tests.</a> Attention, Perception, &amp; Psychophysics. 77 (2), 692-700 (2015).</li><li>Kunimoto, C., Miller, J., Pashler, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Confidence+and+accuracy+of+near-threshold+discrimination+responses.">Confidence and accuracy of near-threshold discrimination responses.</a> Consciousness and Cognition. 10 (3), 294-340 (2001).</li><li>Puputti, S., Hoppu, U., Sandell, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Taste+sensitivity+Is+associated+with+food+consumption+behavior+but+not+with+recalled+pleasantness.">Taste sensitivity Is associated with food consumption behavior but not with recalled pleasantness.</a> Foods. 8 (10), 444 (2019).</li><li>Mennella, J. A., Pepino, M. Y., Reed, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+and+environmental+determinants+of+bitter+perception+and+sweet+preferences.">Genetic and environmental determinants of bitter perception and sweet preferences.</a> Pediatrics. 115 (2), 216-222 (2005).</li><li>Anliker, J. A., Bartoshuk, L., Ferris, A. M., Hooks, L. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Children's+food+preferences+and+genetic+sensitivity+to+the+bitter+taste+of+6-n-propylthiouracil+(PROP).">Children's food preferences and genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP).</a> American Journal of Nutrition. 54 (2), 316-320 (1991).</li><li>Okronipa, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exposure+to+a+slightly+sweet+lipid-based+nutrient+supplement+during+early+life+does+not+increase+the+level+of+sweet+taste+most+preferred+among+4-+to+6-year-old+Ghanaian+children:+follow-up+of+a+randomized+controlled+trial.">Exposure to a slightly sweet lipid-based nutrient supplement during early life does not increase the level of sweet taste most preferred among 4- to 6-year-old Ghanaian children: follow-up of a randomized controlled trial.</a> The American Journal of Clinical Nutrition. 109 (4), 1224-1232 (2019).</li><li>Murphy, C., Han, S. S., Coons, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+age+on+taste+sensitivity.">The effect of age on taste sensitivity.</a> Special senses in aging: A current biological assessment. , 21-33 (1979).</li><li>Moore, L. M., Nielsen, C. R., Mistretta, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sucrose+taste+thresholds:+age-related+differences.">Sucrose taste thresholds: age-related differences.</a> Journal of Gerontology. 37 (1), 64-69 (1982).</li><li>Richter, C. P., Campbell, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sucrose+taste+thresholds+of+rats+and+humans.">Sucrose taste thresholds of rats and humans.</a> American Journal of Physiology. 128, 291-297 (1940).</li><li>Schiffman, S. S., Sattely-Miller, E. A., Zimmerman, I. A., Graham, B. G., Erickson, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Taste+perception+of+monosodium+glutamate+(MSG)+in+foods+in+young+and+elderly+subjects.">Taste perception of monosodium glutamate (MSG) in foods in young and elderly subjects.</a> Physiology &amp; Behavior. 56 (2), 265-275 (1994).</li><li>Mennella, J. A., Pepino, M. Y., Duke, F. F., Reed, D. 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The authors declare they have no competing financial interests.

The TDT test is a two-alternative, forced-choice, staircase procedure that uses strict rules to meet criteria than prior methods12, thus ensuring a more stable outcome measure. Using criteria established at the Monell-Jefferson Chemosensory Clinical Research Center2, the TDT is a reliable swish-and-spit method that measures the lowest concentration of sucrose, NaCl, or MSG in solution that can be detected by taste among individuals as young as 6 years. If completed as described, including enforcing participants rinsing their mouths before and after each tasting, the results are reliable and quick and provide insight into an important dimension of taste that is independent of hedonics8.
Although the application of psychophysical tools to measure this dimension of taste is well established in the field, many methods have not been validated for use in children14. There are several critical steps in the protocol, some of which apply particularly to children [see also reference15]. First, criteria for attaining threshold should not rely solely on the occurrence of any four reversals or vary due to the age of the participant. Rather, there should be a maximum of two dilution steps between two successive reversals, and the series of reversals should not form an ascending pattern, which may be the case when the participant is simply guessing or not attending to the task. These additional criteria, which were established based on clinical experience2, allow for the evaluation of the functioning of the taste system of the individual, in part because they control for false positives, especially when the participant is simply guessing16.
Second, the procedure is forced-choice, so if participants respond that &#34;neither&#34; or &#34;both&#34; solutions have a taste, that answer is not accepted. Rather, they are told to &#34;guess.&#34; During TDT, participants often feel like they are guessing, but that should not be accepted as evidence that they are completely unaware of the taste stimuli17. Moreover, individuals may vary in their internal criteria for what constitutes a taste sensation and hence, their willingness to say that a solution does or does not have a taste. Third, because the recency of eating affects taste perception18, standardizing the time since the participant last ate or drank anything but water is important to reduce intersubject variability caused by sensory adaptation or enhancement. Fourth, the tastants used herein are palatable and presented in solution, not in a food matrix. When a food matrix is used, longer interstimulus intervals might be required for foods to clear the palate. While this method has been used to measure detection thresholds for sour or bitter tastants among adults2,11, its use to measure detection thresholds for unpalatable tastants among some young children may be problematic due to their heightened sensitivity to some bitter tastants and their potential unwillingness to continue participation19.
A forced-choice procedure of presenting up to four pairs of ascending concentrations of bitter-tasting solutions and dH2O has been successful for pediatric populations19,20. Fifth, embedded in the context of a game, the method is sensitive to the cognitive and language limitations of children, and requires only that the participant point to the cup that contains the taste. In a recent study, 80% of the children provided sustained attention for, on average, 15 min and reached criteria8. Such information on completion of the tasks should be reported, particularly when pediatric populations are studied.
The present method has real-world relevance and has been used for assessing detection thresholds for the other basic tastes of sour (citric acid) and bitter (quinine)2 and in adults of varying ages8. Because the method does not require verbal responses, the instructions should easily be translated to other languages21, making it a valuable psychophysical tool for scientists worldwide. However, like any other psychophysical methods, there will likely be limitations in its use, particularly with younger children. The procedure may be more difficult to attain criteria for children than for adults. In one study, 20% of children did not reach criteria, compared to 5% of adults8. Reasons for non-completion included unfocused behavior, failure to understand the task, or becoming fatigued and unable to continue.
Findings from studies that used this taste TDT have contributed extensively to the diagnosis of taste ageusia in the clinic and have furthered the understanding of how taste sensitivity changes with age and health status. Clinical evaluation of patients revealed that sucrose detection thresholds &#8805; 0.025 M for both sexes and NaCl detection thresholds &#8805; 0.012 M for men or &#8805; 0.010 M for women are considered abnormal2. Among adults, there is a gradual decline in taste sensitivity for sweet, salty, sour, and bitter tastes that continues into the eighth decade22. Younger adults typically have lower taste detection thresholds (are more sensitive) than are older adults22,23,24,25. However, children and adolescents have taste thresholds for sucrose that are higher (less sensitive)8 and that are lower (more sensitive) than those of adults for the bitter taste of propylthiouracil, with the adult pattern emerging during adolescence19,26.
Taste detection thresholds have been shown to be related to indicators of health. For example, salt taste detection thresholds positively correlated with systolic blood pressure among children who were normal weight7, whereas children with central obesity had lower detection thresholds for sucrose (more sensitive) than those without central obesity4, with similar findings among adolescents27. However, the relationship between obesity and sucrose detection thresholds was not observed in adult women, and adult women with obesity had higher detection thresholds (were less sensitive) to the savory taste of MSG9.
While research on the differences in detection thresholds between children and adults are limited, it is known that sucrose taste detection thresholds do not predict sweet taste preferences or suprathreshold intensity ratings from childhood to adulthood8,28,29, providing further evidence that taste sensitivity represents a distinct dimension of taste that is independent of preferences and thus suggesting different underlying mechanisms. Greater understanding of the complex interplay among age, dietary habits, health status, and the sensitivity of the taste system, and whether such interactions differs among the primary tastants, is an important area for future research.

The sense of taste functions as a gatekeeper, determining in part whether an individual rejects a food or liquid or accepts it into the oral cavity. Taste psychophysics-the study of relationships between distinct chemical stimuli and the sensations and perceptions they produce-provides important information on the functioning of the taste system1. Not only are there several basic tastes (sweet, salty, bitter, sour, umami), but each taste quality can be characterized by distinct perceptual dimensions, including how sensitive individuals are in detecting the chemical stimulus or recognizing its taste, and how much they like or dislike the taste sensation.
This article describes a psychophysical method that can be used to reliably measure taste detection thresholds&#160;(i.e., the lowest concentration of a tastant that can be detected) in individuals as young as 6 years. From childhood to adulthood, detection thresholds have been used in clinical assessments of the effects of trauma or disease states2,3 and in basic research applications, to study the effects of diet, aging, development, obesity, and smoking on the taste system, as well as genotype-taste phenotype relationships4,5,6,7,8,9,10,11.
This taste detection threshold&#160;(TDT) test, which typically takes an average of 15 min per stimulus (range: 4-35 min; median: 13 min) to complete, consists of a two-alternative, forced-choice, staircase, tracking procedure that has been used to measure the lowest concentration of sucrose, sodium chloride (NaCl), or monosodium glutamate (MSG) in solution that can be detected as a taste. As outlined herein, participants are presented with pairs of solutions; in each pair, one solution is water, and the other solution contains varying concentrations of the tastant. Using a whole-mouth-tasting method, participants taste each solution (without swallowing) and then point to the solution with a taste or that tastes different from water. The concentration of the stimulus in the subsequent pair increases after a single incorrect response and decreases after two consecutive correct responses. A reversal occurs when the concentration sequence changes direction.
The task is deemed completed after the occurrence of four reversals, provided there are a maximum of two dilution steps between two successive reversals, and the series of reversals do not form an ascending pattern. These additional criteria, which were established in clinical practice by Dr. Cowart and colleagues at the Monell-Jefferson Chemosensory Clinical Research Center2, ensure greater reliability in outcomes and enhance confidence in the validity of individual measures of taste functioning. Research studies have used this method to determine taste detection thresholds for sucrose, salt, or MSG in hundreds of healthy children as young as 6 years, adolescents, and adults4,5,6,7,8,9,10,11 and have demonstrated that the majority (&#62;~80%) of children can complete the psychophysical task4,6,7,8, highlighting the appropriateness of the method for pediatric populations.

<table><tbody><tr><td>Digital stopwatch</td><td>Fisherbrand</td><td>14-649-7</td><td></td></tr><tr><td>Funnel</td><td>Thermo Scientific</td><td>10-348D</td><td></td></tr><tr><td>Glass beaker, 2000 mL</td><td>Cole-Parmer</td><td>NC0821737</td><td></td></tr><tr><td>Glass bottles with lids, 120 mL (25)</td><td>Fisherbrand</td><td>FB02911904</td><td></td></tr><tr><td>Glass bottles with lids, 950 mL (17)</td><td>Fisherbrand</td><td>FB02911903</td><td></td></tr><tr><td>Graduated glass cylinders, 100 mL</td><td>PYREX</td><td>08-552E</td><td></td></tr><tr><td>Graduated glass cylinders, 1000 mL</td><td>PYREX</td><td>08-566G</td><td></td></tr><tr><td>Graduated glass cylinders, 50 mL</td><td>PYREX</td><td>08-566C</td><td></td></tr><tr><td>Graduated glass cylinders, 500 mL</td><td>PYREX</td><td>08-566F</td><td></td></tr><tr><td>Medicine cups</td><td>Medline</td><td>22-666-470</td><td></td></tr><tr><td>Mini Cupcake, 48-cup Muffin pan (2)</td><td>Wilton&amp;nbsp;</td><td>NA</td><td></td></tr><tr><td>Monosodium glutamate (MSG)</td><td>Ajinomoto</td><td>NA</td><td></td></tr><tr><td>Pipet Fillers</td><td>Thermo Scientific</td><td>14-387-163</td><td></td></tr><tr><td>Pipets 50 mL</td><td>Fisherbrand</td><td>13-676-10Q</td><td></td></tr><tr><td>Sodium chloride (NaCl)</td><td>Morton</td><td>NA</td><td></td></tr><tr><td>Sucrose, Crystal, NF</td><td>Spectrum Chemical MFG Corp</td><td>57-50-1</td><td></td></tr><tr><td>Volumetric flask, 2000 mL, with stopper</td><td>PYREX</td><td>10-210H</td><td></td></tr><tr><td>Volumetric flasks, 1000 mL, with stoppers (4)</td><td>PYREX</td><td>10-210G</td><td></td></tr><tr><td>Weight boats</td><td>Sartorius</td><td>13-735-744</td><td></td></tr></tbody></table>

psychophysical tracking method to assess taste detection thresholds in children, adolescents, and adults: the taste detection threshold (tdt) test

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a reliable measure of sweet, salty, and umami taste detection thresholds from childhood to adulthood. Advantages of the method include procedures that are identical for children and adults, thus allowing the determination of age-related and individual differences in taste perception, if any, and tasks that can be completed in a relatively short time frame, do not rely on continuous attention or require memorization, control for subjective response biases, and minimize the impact of language development. After a 1 hour fast, participants are presented with pairs of solutions; in each pair, one solution is water, and the other solution contains varying concentrations of the tastant.
Using a whole-mouth tasting method, participants taste each solution (without swallowing and with rinsing between tastings) and then point to the solution with a taste or that tastes different from water. The concentration of the stimulus in the subsequent pair increases after a single incorrect response and decreases after two consecutive correct responses. A reversal occurs when the concentration sequence changes direction. The task is deemed completed after the occurrence of four reversals, provided there are a maximum of two dilution steps between two successive reversals, and the series of reversals do not form an ascending pattern. These additional criteria ensure greater reliability in outcomes. The TDT is then calculated as the geometric mean of the concentrations of the four reversals. This method has real-world relevance as it provides information on a dimension of taste perception that is independent of hedonics, and that can change with aging and certain disease states, making it a valuable psychophysical test.

Figure 4&#160;illustrates the tracking grid results from four representative participants (A-D). Reversals, which are changes in the direction of the participant&#39;s responses, are denoted by circles and numbered in order of occurrence to illustrate when the criteria are met. Reversals are color-coded to illustrate when the change in direction goes from incorrect to correct (green) or from correct to incorrect (red).
Figure 4A shows the tracking grid from a participant whose responses met the criteria within the first four reversals. In order of occurrence, reversals for this participant occurred at steps 8, 9, 8, and 10. This sequence met the criteria because (a) there were no more than two steps between any two successive reversals (step 8&#160;vs&#160;9, 9&#160;vs&#160;8, 8&#160;vs 10), and (b) there were two sets of pairs in which the participant correctly identified the T twice at the same step (8). The detection threshold for this participant is determined by the geometric mean of the concentrations of those four reversals:
<img alt="Equation 2" src="/files/ftp_upload/62384/62384eq02.jpg" />
Geometric mean = 0.0065 M
Figure 4B shows the tracking grid from a participant&#160;with a relatively high sucrose detection threshold (low sensitivity) whose responses in the first four reversals did not meet the criteria. In order of occurrence, the first four reversals occurred at steps 9, 10, 8, and 9. Although these reversals were within two steps of each other (9&#160;vs&#160;10, 10 vs&#160;8, 8&#160;vs&#160;9), there were not two sets of pairs in which the participant correctly identified the T twice at the same step (8&#160;vs&#160;9). These reversals formed an ascending pattern; therefore, criteria were not met and testing continued. Reversals 6-9 met the criteria because there were (a) no more than two steps between any two successive reversals (step 8&#160;vs&#160;6, 6&#160;vs&#160;7, 7&#160;vs&#160;6), and (b) two sets of two correct answers in a row were obtained at the same step (step 6). The detection threshold for this participant is determined by the geometric mean of the concentrations of those four reversals:
<img alt="Equation 3" src="/files/ftp_upload/62384/62384eq03.jpg" />
Geometric mean&#160;= 0.021 M
Figure 4C shows the tracking grid from a participant&#160;with a relatively low sucrose detection threshold (high sensitivity) whose responses in the first four reversals did not meet the criteria. Reversals occurred at steps 9, 10, 9, and 13. Although in two pairs (pairs 3-4 and 7-8), the participant correctly identified the tastant twice at the same step (step 9), there were more than two steps between reversals 3 and 4 (step 9&#160;vs&#160;13). Thus, testing continued. The last four reversals (steps 13, 12, 13, 12) met the criteria because (a) there were no more than two steps between any two successive reversals (13&#160;vs&#160;12), and (b) the participant correctly identified the same concentration (step 12) when given pairs 17-18 and 20-21. The detection threshold for this participant is determined by the geometric mean of the concentrations of those four reversals:
<img alt="Equation 4" src="/files/ftp_upload/62384/62384eq04.jpg" />
Geometric mean&#160;= 0.00075 M
Figure 4D shows the tracking grid from a participant with a relatively high sucrose detection threshold (low sensitivity) whose responses met the criteria within the first four reversals (steps 6, 7, 5, 8). There were no more than two steps between any two successive reversals (6&#160;vs&#160;7, 7&#160;vs&#160;5, 5&#160;vs&#160;8), and the participant correctly identified the same concentration (step 6) when given pairs 7-8 and 13-14. The detection threshold for this participant is determined by the geometric mean of the concentrations of those four reversals:
<img alt="Equation 5" src="/files/ftp_upload/62384/62384eq05.jpg" />
Geometric mean&#160;= 0.024 M
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/62384/62384fig04.jpg" /> 
Figure 4: Tracking grids. (A-D) Representative data from four subjects. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62384/62384fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold TDT Test at JoVE.com

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold TDT Test

Psychophysical tools measure the functionality of the taste system for both research and health assessment purposes. This paper describes a method to measure taste detection thresholds that can determine the lowest concentration of sucrose, sodium chloride, or monosodium glutamate that can be tasted by individuals as young as 6 years.

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold (TDT) Test

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a ...

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Nanyang Technological University

Research

JoVE Journal

Medicine

4.4K Views.  National Institute of Alcohol Abuse and Alcoholism, Section of Sensory Science and Metabolism. Dit protocol beschrijft een methode die de gevoeligheid van het smaaksysteem meet. Dit is een belangrijke dimensie van smaak die onafhankelijk is van smaakhedonie. De TDT-test kan worden gebruikt bij oud en jong.Het is heel gemakkelijk te begrijpen. Het duurt minder dan 15 minuten om te voltooien en maakt gebruik van een zeer strikte reeks criteria die zorgen voor een stabiele uitkomstmaat. Deelnemers moeten comfortabel en goed geïnformeerd zijn, en als ze niet weten welke van de paar...

Video: Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold TDT Test

Measurement of Vibration Detection Threshold and Tactile Spatial Acuity in Human Subjects

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about mechanosensory function that are relevant for clinical diagnosis as well as for basic research. Here, we describe two psychophysical tests designed to determine the vibration detection threshold (automated system) and tactile spatial acuity (handheld device). Both procedures implement a two-interval forced-choice and a transformed-rule up and down experimental paradigm. These tests have been used to obtain mechanosensory profiles for individuals from distinct human cohorts such as twins or people with sensorineural deafness.

Here, we present protocols to determine vibration detection thresholds and tactile acuity using psychophysical methods in man.

Tests that allow the precise determination of psychophysical thresholds for vibration and grating orientation provide valuable information about ...

Behavior

Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to adulthood. The method, which is identical for children, adolescents, and adults, is of short duration (&#60; 15 min), does not rely on sustained attention or place demands on memory (which would yield spurious age differences), and minimizes the impact of language development, making this method amenable to the cognitive limitations of pediatric populations. In this whole-mouth tasting method, subjects are asked to taste (without swallowing) pairs of solutions of different sucrose concentrations and to point to the solution they prefer. Each subsequent pair contains the participant&#39;s preceding preferred concentration and an adjacent stimulus concentration. The procedure continues until the subject chooses either a given concentration of sucrose when paired with both a higher and a lower concentration, or the highest or lowest concentration two consecutive times. Subjects are prevented from reaching response criteria on the basis of first or second position bias by the two-series design of the method, which counterbalances the order of solution presentation within each pair between the series (the weaker concentration is presented first in Series 1, second in Series 2). The geometric mean of the two sucrose concentrations chosen in Series 1 and 2 is an estimate of the participant&#39;s most preferred level of sucrose. Sucrose preference as determined with this laboratory-based measure has been shown to be associated with preference for sugars in foods and beverages and with taste receptor genotype, family history of alcoholism, and race/ethnicity, as well as depressive symptomatology among pediatric populations. The method has real-world relevance and has been applied to determine most preferred level of other tastes (e.g., salt), making it a valuable psychophysical tool.

Sweet taste has powerful hedonic appeal among people of all ages, particularly children. Described herein is a reliable and valid method that can be used to determine the level of sweetness most preferred, making it a valuable psychophysical tool for scientists.

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to ...

Psychophysically-anchored, Robust Thresholding in Studying Pain-related Lateralization of Oscillatory Prestimulus Activity

In perceptual studies, it is often important to objectively assess the equality of delivered stimulation across participants or to quantify the intra-individual sensation magnitude that is evoked by stimulation over multiple trials. This requires a robust mapping of stimulus magnitude to perceived intensity and is commonly achieved by psychophysical estimation methods such as the staircase procedure. Newer, more efficient procedures like the QUEST algorithm fit a psychophysical function to the data in real time while at the same time maximizing the efficiency of data collection. A robust estimate of the threshold intensity between painful and nonpainful perceptions can then be used to reduce the influence of variations in sensory input in subsequent analyses of oscillatory brain activity. By stimulating at a constant threshold intensity determined by an adaptive estimation procedure, the variance in the ratings can be directly attributed to perceptual processes. Oscillatory activity can then be contrasted between &#34;pain&#34; and &#34;no-pain&#34; trials directly, yielding activity that closely relates to perceptual classification processes in nociception.

Psychophysical methods such as the QUEST estimation procedure can efficiently yield robust estimates of the stimulation intensity at which nonpainful sensations transition into painful sensations. By stimulating repeatedly at the threshold intensity, the variability in rating responses can directly be attributed to perceptual classifications in subsequent analyses.

In perceptual studies, it is often important to objectively assess the equality of delivered stimulation across participants or to quantify the ...

Assessment of Midline Lingual Point-Pressure Somatosensation Using Von Frey Hair Monofilaments

Detection and discrimination threshold estimates for oral point pressure are assessed using Von Frey Hair monofilaments. Consistent with previously published protocols, threshold estimates are determined using a two-interval forced choice (2-IFC) paradigm with a three down/one up approach. Detection threshold estimates determine the mean force in which a participant can identify the presence of pressure. During the detection threshold procedure, the participant is instructed to choose which of two sequentially presented observation intervals contained the tactile test stimulus. If the participant performs three correct detections in a row (i.e., 3 &#39;hits&#39;), the researcher decreases the stimulus to the next lower target force level. With one incorrect detection (a &#39;miss&#39;), the researcher increases the force delivered to the next higher level. This threshold estimation approach is known as a 3-down/1-up adaptive staircase. Reponses are recorded on a paper ballot, and a participant&#39;s estimated threshold is defined as the geometric mean of five reversals. During the discrimination threshold procedure, the participant is asked to make a choice between two serially presented stimuli as to which is the &#34;harder&#34; or &#34;stronger&#34; pressure. The same scoring of &#39;hits&#39;, &#39;misses&#39;, and stopping points are used. Detection and discrimination testing for oral point pressure at tongue midline takes approximately 20 min to complete. Using these commercially-available clinical tools, individual touch sensation profiles for the midline tongue can be achieved in a relatively time and cost effective means.

This work describes a standard method to assess tactile sensation at the midline of the tongue tip. Using Von Frey Hair (VFH) monofilaments, this protocol provides estimates of detection and discrimination threshold estimates for oral point pressure (OPP).

Detection and discrimination threshold estimates for oral point pressure are assessed using Von Frey Hair monofilaments. Consistent with previously ...

Assessment of Spatial Lingual Tactile Sensitivity using a Gratings Orientation Test

Individual thresholds by R-index estimates are calculated using a gratings orientation test (6 different tools of increasing grating size from 0.20-1.25 mm) to assess spatial lingual tactile sensitivity. During the experiment, the subjects are blindfolded and asked to specify the orientation of the grating (either horizontal or vertical) placed on the tongue. R-index is based on Signal Detection Theory (SDT), and it is an estimated probability of correctly identifying a target stimulus (the signal, e.g., the correct orientation) compared to an alternative stimulus (the noise, e.g., the incorrect orientation). Once the R-index values for each subject and each tool dimension are calculated, it is possible to derive the individual threshold by interpolating the two R-indices immediately below and above the established cut-off (typically 75%) based on one-sided R-index critical values. This procedure can be helpful in the medical field to study the association between oral tactile sensitivity, speech clarity, and swallowing disorders, as well as in sensory and consumer studies to explore individual variation in texture perception, food preferences, and eating behavior.

This work illustrates a standard procedure and threshold determination by the R-index to assess spatial lingual tactile sensitivity using a gratings orientation test.

Individual thresholds by R-index estimates are calculated using a gratings orientation test (6 different tools of increasing grating size from 0.20-1.25 ...

New Methods to Study Gustatory Coding

The sense of taste allows animals to detect chemicals in the environment, giving rise to behaviors critical for survival. When Gustatory Receptor Neurons (GRNs) detect tastant molecules, they encode information about the identity and concentration of the tastant as patterns of electrical activity that then propagate to follower neurons in the brain. These patterns constitute internal representations of the tastant, which then allow the animal to select actions and form memories. The use of relatively simple animal models has been a powerful tool to study basic principles in sensory coding. Here, we propose three new methods to study gustatory coding using the moth Manduca sexta. First, we present a dissection procedure for exposing the maxillary nerves and the subesophageal zone (SEZ), allowing recording of the activity of GRNs from their axons. Second, we describe the use of extracellular electrodes to record the activity of multiple GRNs by placing tetrode wires directly into the maxillary nerve. Third, we present a new system for delivering and monitoring, with high temporal precision, pulses of different tastants. These methods allow the characterization of neuronal responses in vivo directly from GRNs before, during and after tastants are delivered. We provide examples of voltage traces recorded from multiple GRNs, and present an example of how a spike sorting technique can be applied to the data to identify the responses of individual neurons. Finally, to validate our recording approach, we compare extracellular recordings obtained from GRNs with tetrodes to intracellular recordings obtained with sharp glass electrodes.

We present three new methods to study gustatory coding. Using a simple animal, the moth Manduca sexta (Manduca), we describe a dissection protocol, the use of extracellular tetrodes to record the activity of multiple gustatory receptor neurons, and a system for delivering and monitoring precisely timed pulses of tastants.

The sense of taste allows animals to detect chemicals in the environment, giving rise to behaviors critical for survival. When Gustatory Receptor Neurons ...

Neuroscience

Taste Exam: A Brief and Validated Test

The emerging importance of taste in medicine and biomedical research, and new knowledge about its genetic underpinnings, has motivated us to supplement classic taste-testing methods in two ways. First, we explain how to do a brief assessment of the mouth, including the tongue, to ensure that taste papillae are present and to note evidence of relevant disease. Second, we draw on genetics to validate taste test data by comparing reports of perceived bitterness intensity and inborn receptor genotypes. Discordance between objective measures of genotype and subjective reports of taste experience can identify data collection errors, distracted subjects or those who have not understood or followed instructions. Our expectation is that fast and valid taste tests may persuade researchers and clinicians to assess taste regularly, making taste testing as common as testing for hearing and vision. Finally, because many tissues of the body express taste receptors, taste responses may provide a proxy for tissue sensitivity elsewhere in the body and, thereby, serve as a rapid, point-of-care test to guide diagnosis and a research tool to evaluate taste receptor protein function.

This protocol measures human taste responses and includes a brief anatomical assessment, a short taste test, and a validation method using the subject&#39;s reported sensation and taste receptor genotype.

The emerging importance of taste in medicine and biomedical research, and new knowledge about its genetic underpinnings, has motivated us to supplement ...

Open-Source Real-Time Closed-Loop Electrical Threshold Tracking for Translational Pain Research

Nociceptors are a class of primary afferent neurons that signal potentially harmful noxious stimuli. An increase in nociceptor excitability occurs in acute and chronic pain conditions. This produces abnormal ongoing activity or reduced activation thresholds to noxious stimuli. Identifying the cause of this increased excitability is required for the development and validation of mechanism-based treatments. Single-neuron electrical threshold tracking can quantify nociceptor excitability. Therefore, we have developed an application to allow such measurements and demonstrate its use in humans and rodents. APTrack provides real-time data visualization and action potential identification using a temporal raster plot. Algorithms detect action potentials by threshold crossing and monitor their latency after electrical stimulation. The plugin then modulates the electrical stimulation amplitude using an up-down method to estimate the electrical threshold of the nociceptors. The software was built upon the Open Ephys system (V0.54) and coded in C++ using the JUCE framework. It runs on Windows, Linux, and Mac operating systems. The open-source code is available (<a data-saferedirecturl="https://www.google.com/url?q=https://github.com/Microneurography/APTrack&amp;source=gmail&amp;ust=1680789829274000&amp;usg=AOvVaw0nMk9J_EI2jUn8SlmC5JJm" href="https://github.com/Microneurography/APTrack" target="_blank">https://github.com/Microneurography/APTrack</a>). The electrophysiological recordings were taken from nociceptors in both a mouse skin-nerve preparation using the teased fiber method in the saphenous nerve and in healthy human volunteers using microneurography in the superficial peroneal nerve. Nociceptors were classified by their response to thermal and mechanical stimuli, as well as by monitoring the activity-dependent slowing of the conduction velocity. The software facilitated the experiment by simplifying the action potential identification through the temporal raster plot. We demonstrate real-time closed-loop electrical threshold tracking of single-neuron action potentials during&#160;in vivo&#160;human microneurography, for the first time, and during&#160;ex vivo&#160;mouse electrophysiological recordings of C-fibers and A&#948;-fibers. We establish proof of principle by showing that the electrical threshold of a human heat-sensitive C-fiber nociceptor is reduced by heating the receptive field. This plugin enables the electrical threshold tracking of single-neuron action potentials and allows the quantification of changes in nociceptor excitability.

APTrack is a software plugin developed for the Open Ephys platform that enables real-time data visualization and the closed-loop electrical threshold tracking of neuronal action potentials. We have successfully used this in microneurography for human C-fiber nociceptors and mouse C-fiber and A&#948;-fiber nociceptors.

Nociceptors are a class of primary afferent neurons that signal potentially harmful noxious stimuli. An increase in nociceptor excitability occurs in ...

A Novel Method for Enhanced Analysis of Insect Taste Neuron Activity

Base Recording: A Technique for Analyzing Responses of Taste Neurons in Drosophila

Insects taste the external world through taste hairs, or sensilla, that have pores at their tips. When a sensillum comes into contact with a potential food source, compounds from the food source enter through the pore and activate neurons within. For over 50 years, these responses have been recorded using a technique called tip recording. However, this method has major limitations, including the inability to measure neural activity before or after stimulus contact and the requirement for tastants to be soluble in aqueous solutions. We describe here a technique that we call base recording, which overcomes these limitations. Base recording allows the measurement of taste neuron activity before, during, and after the stimulus. Thus, it allows extensive analysis of OFF responses that occur after a taste stimulus. It can be used to study hydrophobic compounds such as long-chain pheromones that have very low solubility in water. In summary, base recording offers the advantages of single-sensillum electrophysiology as a means of measuring neuronal activity - high spatial and temporal resolution, without the need for genetic tools - and overcomes key limitations of the traditional tip recording technique.

Author Spotlight: Advances in Chemoreception &#8211; From Insect Odor Receptors to Non-Coding RNAs

A rarely used method of electrophysiological recording, base recording, allows analysis of features of taste coding that cannot be examined by conventional recording methods. Base recording also allows the analysis of taste responses to hydrophobic stimuli that cannot be studied using traditional electrophysiological methods.

Insects taste the external world through taste hairs, or sensilla, that have pores at their tips. When a sensillum comes into contact with a potential ...

The Staircase Procedure for Finding a Perceptual Threshold

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University
Psychophysics is the name for a set of methods in perceptual psychology designed in order to relate the actual intensity of stimuli to their perceptual intensity. One important aspect of psychophysics involves the measurement of perceptual thresholds: How bright does a light need to be for a person to be able to detect it? How little pressure applied to the skin is detectable? How soft can a sound be and still be heard? Put another way, what are the smallest amounts of stimulation that humans can sense? The staircase procedure is an efficient technique for identifying a person&#39;s perceptual threshold.

This video will demonstrate standard methods for applying the staircase procedure in order to identify a person&#39;s auditory threshold, that is, the minimal volume necessary for a tone to be perceived.

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University
Psychophysics is the name for a set of methods in perceptual psychology designed in ...

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold (TDT) Test

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