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. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age+modifies+the+genotype-phenotype+relationship+for+the+bitter+receptor+TAS2R38.">Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38.</a> BMC Genetics. 11, 60 (2010).</li><li>Pasquet, P., Frelut, M. L., Simmen, B., Hladik, C. M., Monneuse, M. O. <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+in+massively+obese+and+in+non-obese+adolescents.">Taste perception in massively obese and in non-obese adolescents.</a> International Journal of Pediatric Obesity. 2 (4), 242-248 (2007).</li><li>Snyder, D. J., Prescott, J., 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=Modern+psychophysics+and+the+assessment+of+human+oral+sensation.">Modern psychophysics and the assessment of human oral sensation.</a> Advances in Otorhinolaryngology. 63, 221-241 (2006).</li><li>Webb, J., Bolhuis, D. P., Cicerale, S., Hayes, J. E., Keast, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationships+between+common+measurements+of+taste+function.">The relationships between common measurements of taste function.</a> Chemosensory Perception. 8 (1), 11-18 (2015).</li></ol>

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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<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&#160;</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/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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4.2K Views.  National Institute of Alcohol Abuse and Alcoholism, Section of Sensory Science and Metabolism. 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.

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

Technique to Collect Fungiform (Taste) Papillae from Human Tongue

The sense of taste is critical for human life. It informs the body about the quality of food that will be potentially ingested and stimulates metabolic processes that prepare the alimentary canal for digestion. Steady progress is being made towards understanding the early biochemical and molecular events underlying taste transduction (for a review, Breslin and Spector, 20081). However, progress to date has largely resulted from animal models. Yet, since marked differences in receptor specificity and receptor density vary among species, human taste transduction will only be understood by using human taste tissue. Here we describe a biopsy technique to collect human fungiform papillae, visible as rounded pink anterior structures, about 0.5 mm in diameter that contain taste buds. These biopsied papillae are used for several purposes including the isolation of viable taste bud cells, in situ hybridization, immunohistochemistry and, through techniques of molecular biology, the identification of taste-specific novel proteins.

Technique to Collect Fungiform Taste Papillae from Human Tongue

Knowledge of molecular mechanisms underlying gustatory transduction has recently enjoyed significant advances, largely due to using animal models. However, the wide diversity in taste sensitivity and specificity among mammals warrants studies in human tissue. We describe a biopsy technique to collect living taste cells from the papillae on human tongue.

The sense of taste is critical for human life. It informs the body about the quality of food that will be potentially ingested and stimulates metabolic ...

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

Quantitative Visualization and Detection of Skin Cancer Using Dynamic Thermal Imaging

In 2010 approximately 68,720 melanomas will be diagnosed in the US alone, with around 8,650 resulting in death 1. To date, the only effective treatment for melanoma remains surgical excision, therefore, the key to extended survival is early detection 2,3. Considering the large numbers of patients diagnosed every year and the limitations in accessing specialized care quickly, the development of objective in vivo diagnostic instruments to aid the diagnosis is essential. New techniques to detect skin cancer, especially non-invasive diagnostic tools, are being explored in numerous laboratories. Along with the surgical methods, techniques such as digital photography, dermoscopy, multispectral imaging systems (MelaFind), laser-based systems (confocal scanning laser microscopy, laser doppler perfusion imaging, optical coherence tomography), ultrasound, magnetic resonance imaging, are being tested. Each technique offers unique advantages and disadvantages, many of which pose a compromise between effectiveness and accuracy versus ease of use and cost considerations. Details about these techniques and comparisons are available in the literature 4.
Infrared (IR) imaging was shown to be a useful method to diagnose the signs of certain diseases by measuring the local skin temperature. There is a large body of evidence showing that disease or deviation from normal functioning are accompanied by changes of the temperature of the body, which again affect the temperature of the skin 5,6. Accurate data about the temperature of the human body and skin can provide a wealth of information on the processes responsible for heat generation and thermoregulation, in particular the deviation from normal conditions, often caused by disease. However, IR imaging has not been widely recognized in medicine due to the premature use of the technology 7,8 several decades ago, when temperature measurement accuracy and the spatial resolution were inadequate and sophisticated image processing tools were unavailable. This situation changed dramatically in the late 1990s-2000s. Advances in IR instrumentation, implementation of digital image processing algorithms and dynamic IR imaging, which enables scientists to analyze not only the spatial, but also the temporal thermal behavior of the skin 9, allowed breakthroughs in the field.
In our research, we explore the feasibility of IR imaging, combined with theoretical and experimental studies, as a cost effective, non-invasive, in vivo optical measurement technique for tumor detection, with emphasis on the screening and early detection of melanoma 10-13. In this study, we show data obtained in a patient study in which patients that possess a pigmented lesion with a clinical indication for biopsy are selected for imaging. We compared the difference in thermal responses between healthy and malignant tissue and compared our data with biopsy results. We concluded that the increased metabolic activity of the melanoma lesion can be detected by dynamic infrared imaging.

We demonstrated that malignant pigmented lesions with increased metabolic activity generate quantifiable amounts of heat and the measurement of the transient thermal response of the skin to a cooling excitation allows quantitative identification of melanoma and other skin cancers (vs. non-proliferative nevi) at an early stage of the disease.

In 2010 approximately 68,720 melanomas will be diagnosed in the US alone, with around 8,650 resulting in death 1. To date, the only effective treatment ...

Eye Tracking Young Children with Autism

The rise of accessible commercial eye-tracking systems has fueled a rapid increase in their use in psychological and psychiatric research. By providing a direct, detailed and objective measure of gaze behavior, eye-tracking has become a valuable tool for examining abnormal perceptual strategies in clinical populations and has been used to identify disorder-specific characteristics1, promote early identification2, and inform treatment3. In particular, investigators of autism spectrum disorders (ASD) have benefited from integrating eye-tracking into their research paradigms4-7. Eye-tracking has largely been used in these studies to reveal mechanisms underlying impaired task performance8 and abnormal brain functioning9, particularly during the processing of social information1,10-11. While older children and adults with ASD comprise the preponderance of research in this area, eye-tracking may be especially useful for studying young children with the disorder as it offers a non-invasive tool for assessing and quantifying early-emerging developmental abnormalities2,12-13. Implementing eye-tracking with young children with ASD, however, is associated with a number of unique challenges, including issues with compliant behavior resulting from specific task demands and disorder-related psychosocial considerations. In this protocol, we detail methodological considerations for optimizing research design, data acquisition and psychometric analysis while eye-tracking young children with ASD. The provided recommendations are also designed to be more broadly applicable for eye-tracking children with other developmental disabilities. By offering guidelines for best practices in these areas based upon lessons derived from our own work, we hope to help other investigators make sound research design and analysis choices while avoiding common pitfalls that can compromise data acquisition while eye-tracking young children with ASD or other developmental difficulties.

Eye tracking has long been used to study gaze patterns in typically-developing individuals, but recent technological advancements have made its use with clinical populations, including autism, more feasible. While eye-tracking young children with autism can offer insight into early symptom manifestations, it involves methodological challenges. Suggestions for best practices are provided.

The rise of accessible commercial eye-tracking systems has fueled a rapid increase in their use in psychological and psychiatric research. By providing a ...

Cerenkov Luminescence Imaging (CLI) for Cancer Therapy Monitoring

In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities1-3. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues.
 Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI)4-6. CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium7,8. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one 18F decay was estimated to produce an average of 3 photons in water5. 
 Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others4,5,9,10,11. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET.
 Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study12. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor13,14. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.

Cerenkov Luminescence Imaging CLI for Cancer Therapy Monitoring

Use of Cerenkov Luminescence Imaging (CLI) for monitoring preclinical cancer treatment is described here. This method takes advantage of Cerenkov Radiation (CR) and optical imaging (OI) to visualize radiolabeled probes and thus provides an alternative to PET in preclinical therapeutic monitoring and drug screening.

In  molecular imaging, positron emission tomography (PET) and optical imaging (OI)  are two of the most important and thus most widely used modalities1-3. ...

Determining The Electromyographic Fatigue Threshold Following a Single Visit Exercise Test

Theoretically, the electromyographic (EMG) fatigue threshold is the exercise intensity an individual can maintain indefinitely without the need to recruit more motor units which is associated with an increase in the EMG amplitude. Although different protocols have been used to estimate the EMG fatigue threshold they require multiple visits which are impractical for a clinical setting. Here, we present a protocol for estimating the EMG fatigue threshold for cycle ergometry which requires a single visit. This protocol is simple, convenient, and completed within 15-20 min, therefore, has the potential to be translated into a tool that clinicians can use in exercise prescription.

This protocol describes the electromyographic fatigue threshold which demarcates between nonfatiguing and fatiguing exercise workloads. This information could be used to develop a more individualized training program.

Theoretically, the electromyographic (EMG) fatigue threshold is the exercise intensity an individual can maintain indefinitely without the need to recruit ...

Nerve-sparing Mid-urethral Obstruction (NeMO) in Female Small Rodents

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal model to investigate bladder remodeling in pBOO are female rodents undergoing partial obstruction at the proximal urethra. Variability in the degree of obstruction and animal mortality are major concerns with proximal obstruction. Furthermore, dissecting around the proximal urethra and bladder neck jeopardizes bladder innervation.
We developed a nerve-sparing mid-urethral obstruction (NeMO) model for pBOO avoiding the disadvantages of the traditional model. We approached the urethra just inferior to the pubic symphysis, which obviated the need for laparotomy as well as for dissection in this area; also, the striated urethral sphincter remained untouched. We performed NeMO in female Sprague-Dawley rats (12 obstructions, 6 sham animals) as well as in female C57/bl6 mice (20 obstructions, 18 sham animals). After two weeks, we evaluated bladder function, bladder mass, and body mass.
We had no mortalities among obstructed- or sham-operated female rats; as described for the traditional proximal pBOO-method, we tied the suture around the proximal urethra and a temporarily placed 0.9 mm metal rod. NeMO induced an 85% increase in bladder mass after two weeks, average residual urine volume was 0.4 mL in partially obstructed rats while only 0.03 mL in sham animals. In mice, we tested 3 sizes of cannulas that we placed along the urethra when tying the suture. We found that using a 27-gauge cannula resulted in over 50% animal mortality; placing the 25-gauge cannula did not yield the desired response in increasing bladder mass; utilizing a 26-gauge cannula yielded favorable results with minimal animal mortality (1/8) yet a significant 2-fold increase in bladder mass.

Nerve-sparing Mid-urethral Obstruction NeMO in Female Small Rodents

Traditional modeling of partial bladder outlet obstruction in rodents is fraught with animal mortality. A denervation injury from dissection around the proximal urethra and bladder neck is also of major concern. We developed and evaluated a safe and reliable mid-urethral obstruction model, avoiding the shortcomings of the traditional model.

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal ...

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 ...

A Blood-based Test for the Detection of ROS1 and RET Fusion Transcripts from Circulating Ribonucleic Acid Using Digital Polymerase Chain Reaction

We have developed novel methods for the isolation and characterization of tumor-derived circulating ribonucleic acid (cRNA) for blood-based liquid biopsy. Robust detection of cRNA recovered from blood represents a solution to a critical unmet need in clinical diagnostics. The test begins with the collection of whole blood into blood collection tubes containing preservatives that stabilize cRNA. Cell-free, exosomal, and platelet-associated RNA is isolated from plasma in this test system. The cRNA is reverse transcribed to complementary DNA (cDNA) and amplified using digital polymerase chain reaction (dPCR). Samples are evaluated for both the target biomarker as well as a control gene. Test validation included limit of detection, accuracy, and robustness studies with analytic samples. The method developed as a result of these studies reproducibly detect multiple fusion variants for ROS1 (C-Ros proto-oncogene 1; 8 variants) and RET (rearranged during transfection proto-oncogene; 8 variants). The sample processing workflow has been optimized so that test results can consistently be generated within 72 hours of sample receipt.

Detection of circulating ribonucleic acid (cRNA) from blood is an unmet need in clinical diagnostics. Here we describe methods that characterize cRNA from non-small cell lung cancer patients using sensitive and specific digital polymerase chain reaction. The tests meet design requirements to detect fusion variants within 72 hours.

We have developed novel methods for the isolation and characterization of tumor-derived circulating ribonucleic acid (cRNA) for blood-based liquid biopsy. ...

A Novel Non-invasive Method for the Detection of Elevated Intra-compartmental Pressures of the Leg

Acute Compartment Syndrome is a devastating consequence of musculoskeletal trauma. Currently the diagnosis is based on clinical signs and symptoms, and while adjuncts such as invasive intra-compartmental pressure measurements are often used to corroborate the physical exam findings, there remains no reliable objective test to aid in the decision to perform a decompressive fasciotomy. In a cadaver model of compartment syndrome, an ultrasound (US) based method has been shown to be a reliable measurement of increased intra-compartmental pressure. An absolute pressure of &#62;100 mbar or a difference of 50 mbar in the CFFP between the legs can be considered pathologic. Using an ultrasound transducer, coupled with a pressure sensor, the pressure needed to flatten the superficial fascia of the anterior compartment of lower legs (Compartment Fascia Flattening Pressure [CFFP]) can be measured. The CFFP of the injured leg is compared to the CFFP of the uninjured leg. This US measured index can then serve as an adjunct to the physical exam in evaluating injured lower extremities and assessing the need for decompressive fasciotomy. The advantages of this protocol include: being a non-invasive method and an easily reproducible technique.

An ultrasound probe coupled with a pressure sensor is used to assess the intra-compartmental pressure of the leg by directly measuring the compartment fascia flattening pressure (CFFP). This non-invasive protocol will provide reliable assessment of the pressure inside the anterior muscular compartment of the lower leg.

Acute Compartment Syndrome is a devastating consequence of musculoskeletal trauma. Currently the diagnosis is based on clinical signs and symptoms, and ...