[A study of measurements of and factors influencing threshold levels of taste perception].

The threshold levels of taste perception on the right and left side of the tip, root of tongue and soft palate in 60 healthy volunteers were measured by means of an electrogustometry test and a filter-paper disk taste test to confirm the following hypotheses: (1) the threshold on the tip of the tongue was lower than those of the root of the tongue and soft palate, (2) there was a different threshold level between sweet, salty, sour and bitter tastes on the tip of the tongue, (3) some personal properties influenced the person's threshold. Measured threshold levels were compared between these six locations with multiple comparisons. Factors influencing the threshold level on the tip of the tongue, thereafter, were investigated using multivariate logistic regression models. Those factors included sex, age, serological, psychological and behavioral factors. As a result, the thresholds levels on the tip of the tongue were significantly lower than the root of the tongue and soft palate. The thresholds for sweet and bitter taste on the tip of the tongue were also lower than those for salty and sour taste. Increase of age, male, serological increase of zinc and usual alcohol drinking were identified as factors of increase for several thresholds, and increase of anxiety was identified as a factor of decrease for two thresholds of four tastes (sweet, salty, sour and bitter) on the tip of the tongue in the logistic regression models. Increase of depression, mouth breathing, habitual tonus of the tongue and smoking did not appear to be influential factors.