When eating foods, we drive many sensations to acquire information of them. The resultant sensation has evolved to distinguish what kinds of foods, and to judge whether those are able to ingest or not. But in human, the role of this sensation has changed to feel palatability of foods. The basic information for foods palatability, “the flavor”, is the integrative sense that is formed from not only taste but also odors and mouthfeels. In particular, the cross-modal interaction between the gustation and the olfaction is important to form flavor. However, little is known about how and where in the brain flavor is formed. In this review, I describe the important role in the formation of flavor, the mechanism for signal perception and processing, and the neural pathway, of each chemical sense. Finally, I introduce our research which is aimed at revealing the role of the insular cortex in forming flavor, and discuss the flavor as a sense at eating.

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[Purpose] Masticatory muscle activities are often expressed by means of the relative value against the burst at maximum voluntary contraction (MVC), i.e., %MVC ratio. The purpose of this study was to clarify the relation between %MVC ratio of electromyographic bursts of the masseter muscle during daily mastication and maximum bite force.
[Methods] Nineteen females who were clinically diagnosed as bruxism patients participated in this study. A wearable ultraminiature electromyographic device was attached to the unilateral masseteric part of the face on the dominant mastication side, and an electromyogram (EMG) was recorded during daily life. EMG data during meal time on the second day of measurements were analyzed, and EMG bursts longer than 0.08 seconds, with more than three times the baseline amplitude and with an interval to the neighboring burst of 0.08 seconds or more were selected. %MVC ratio, i.e., the value of maximum amplitude of each selected burst divided by the amplitude of MVC, was calculated. The mean %MVC ratio for each subject was calculated. Maximum bite force was measured twice for each subject using Dental Prescale^®, and the mean of the two measurements was used as a representative value for each subject.
[Results] Mean and standard deviation of maximum bite force for the 19 subjects were 518.8 and 327.1 N, respectively. Mean and standard deviation of %MVC ratios during mastication were 64.3 and 27.4 %, respectively. A significant negative correlation was found between maximum bite force and %MVC ratio during mastication (RS=-0.71, p=0.0025).
[Conclusions] The relation between %MVC ratio of electromyographic bursts of the masseter muscle during daily mastication and maximum bite force was elucidated. It was demonstrated that masseteric activity during mastication tended to be expressed as EMG %MVC ratio being higher than the actual force in cases with less maximum bite force. The results suggested that we should carefully interpret EMG results expressed using %MVC ratios in consideration of maximum bite force when we assess the masticatory muscle activity during mastication.

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[Objective] The study aimed to investigate the effect of changes in occlusal contact on postural control via a comparative analysis of the stability limits area, postural sway area, and index of postural stability in the mandibular resting position and under 15% and 30% clenching conditions.
[Materials and Methods] A total of 26 healthy young men without body abnormalities, including those of the stomatognathic system, who gave consent to the study were included as subjects. A foot pressure distribution meter was used to measure the stability limits area and postural sway area and to determine the index of postural stability under each condition.
[Results] There were no significant differences in the stability limits area under each condition, but an enlarging tendency was observed with increased clenching intensity. The postural sway area in the 15% clenching group was significantly reduced compared to the 30% clenching group. The index of postural stability was significantly different between the 15% clenching and 30% clenching group, and the posture was found to be stable in the 15% clenching group.
[Conclusion] Our findings suggest that occlusal contact affects postural control. Because the effects differ according to the clenching intensity in particular, the role of clenching was thought to be different based on different movements and motion patterns.

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