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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.

We report a 65-year-old Japanese female whose primary symptom of myasthenia gravis was related to rhinolalia aperta. The vocal tract during vowel production was evaluated using two-dimensional fast advanced spin echo (2D-FASE) MR images on supine and prone position. Before treatment, MRI on prone position demonstrated anterior shift of the palatine uvula and the tongue during Japanese "a", "u" and "o" production following the gravity, the former suggested the paresis of the sphenosalpingostaphylinus and elevator veli palatini muscle and the latter the paresis of the styloglossal and hypoglossal muscles. After treatment of steroid pulse and immune absorption, 2D-FASE images on prone position revealed the normalized configuration of the tongue and the soft palate during the Japanese five-vowel production. Kinetic MRI may be useful for evaluation of dynamics of the tongue and the soft palate.

The present study investigates the nature of tensor veli palatini muscle (TVP) and levator veli palatini muscle (LVP) as accessory respiratory muscles. In the first part of the study, the relation between the muscles' activities as revealed by EMG activities and respiration rhythm was analysed under various combinations of partial pressures of O2 and CO2 in the arterial blood. Furthermore, the effect of sodium cyanide (NaCN) perfused through the carotid sinus was examined. During resting breathing, no EMG activity was recorded from either muscle. In hypercapnic or hypoxemic conditions produced by rebreathing, TVP exhibited a phasic EMG activity during inspiration. LVP showed a phasic EMG activity during expiration in hypoxic conditions (PaO2 less than 40 mmHg). NaCN perfused bilaterally through the carotid sinus induced the phasic EMG activities similar to those observed in hypercapnia and/or hypoxemia. TVP was more sensitive to NaCN than LVP. The second part of the study examined specific roles of the muscles in altered states of breathing. At the time of onset of LVP activity induced by rebreathing, the oral proportion of airflow markedly increased. On the other hand, TVP activity greatly increased in amplitude when negative pressure was applied to the upper airway. The results suggest that both muscles are accessory respiratory muscles and are regulated by chemogenic inputs including those from the carotid body; TVP is an accessory inspiratory muscle that contributes to the maintenance of upper airway patency, and LVP is an accessory expiratory muscle that increases the portion of expiratory airflow through the oral cavity.