[in Japanese]

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Since the nose and mouth are situated near to each other on the face, olfaction and gustation are generally thought to have close positions in the nervous system to interact with each other. However, neural information about both sensations are not integrated until they reach association cortex. The present review first described the general nature of gustation in comparison with olfaction, and then stated how gustatory information is analyzed or integrated along the central pathway to the gustatory cortex. Further, it described the position of the primary gustatory cortex in humans recently revealed by non-invasive brain imaging and the function of gustation-related cortex, including the primary gustatory cortex.

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The common chemical sense is best exemplified by nerve fibers in the trigeminal (fifth cranial) nerve innervating the mucosa and skin of the mouth, nose, and eyes. The trigeminal nerve consists of three main branches : ophthalmic, maxillary, and mandibular divisions. In the oral cavity, capsaicin and CO₂ are famous compounds that can cause irritation through these nerve fiber endings. A variety of reports indicate that carbonic anhydrase activity is necessary for trigeminal neural responses to carbonated solutions. Contribution of carbonic anhydrase, a zinc-metallo-enzyme, to the normal CO₂-tingling sensation was confirmed by zinc-deficient animal studies.
TRP channels are the vanguard of our sensory systems, responding to temperature, touch, pain,osmolarity, pheromones, taste and other stimuli. But their role is much broader than classical sensory transduction. For example, the capsaicin receptor is a heat-activated ion channel in the pain pathway. TRP channels were briefly reviewed including the reception of irritating volatile organic compounds (VOCs), that were analyzed by calcium fluorimetry for the trigeminal ganglion neurons.
Finally, the interaction between chemoreceptive modalities for taste or odor and irritation was reviewed. Earlier studies indicated that some neuropeptides found in trigeminal nerves can affect the activity of taste receptor cells or chorda tympani nerve responses. These results suggest that oral trigeminal stimulation may modify, at the peripheral level, the detection of at least some taste stimuli, as well as olfactory sensation.

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Feeding behavior is controlled by oral somatosensory as well as chemical senses. Oral somatosensory is including some senses, such as touch, temperature, pain and texture. This review describes about the physiological basis of somatosensory mechanisms elicited by several oral organs, and the relation of chemical senses and these senses.

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This is the summery of our study to examine the fragrance effects on person’s senses. The effect of fragrances to person’s estimation on weight or hot-cold sensation, to texture of the facial treatment cream when used and skin actual feeling after the use was proven. The results suggested that the difference of fragrance influence person’s judgment of various senses. Hereafter we may utilize these fragrance effects as changing the judgment of the senses to make life more heartwarming and to raise the feeling of satisfaction.

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In this review, several studies reporting about interactions between olfactory perception and visual stimuli, e.g. color of odor solution or pictures about odor sources, are introduced. Then, three working hypotheses about interactions between olfaction and vision are discussed. The first hypothesis is that the cross-modal interactions are the result of cross- modal associations between olfactory and visual stimuli. Second is top-down processing activated by visual stimuli affects olfaction. Third is congruency effect. Several studies reporting interactions between olfaction and other sensory/cognitive information, such as gustatory stimuli, somatosensory and kinetic stimuli (body position and sniffing), and knowledge about odor sources are also introduced. These studies suggested that the one who wants to understand individual olfactory world should understand these complex processes in olfactory perception.

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This research deals with unpleasant odors in hospitals with the goal of obtaining the basic information needed for formulating measures to prevent or eliminate such odors. In the study,we conducted a questionnaire survey of 254 nursing staff members at two medical institutions and of 135 non-nursing staff members at one institution. We compared the results with past-related research associated with odors in nursing homes for the aged. 79.1% of the nursing staff and 44.4% of the non-nursing personnel responded that they are bothered by the odors in their hospital. Main areas where odors are strong include sickrooms, sick wards, sanitary rooms and lavatories. Odors from excrement were cited as the most unpleasant, while others such as body odor, chemical odors from medicines, foods odors, tobacco smoke and odors of putrefaction were also mentioned. In the older hospital, higher values were seen particularly for awareness of odors other than that of excrement. Odors accompanied by stains and complex odors were thought to be factors in unpleasantness. It was suggested that to provide a comfortable environment in hospitals it is necessary to control the spread of stool odor, representative of odors that are temporarily strong and unpleasant, as well as complex odors and the urine odor, odors which persist in unpleasantness. The results show that in problem areas such as sickrooms, sick wards, sanitary rooms and lavatories, hospital odors are worse in intensity and unpleasantness than odors present in nursing homes for the aged, suggesting that greater measures to control odors are necessary in hospitals than in nursing homes for the aged.

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