Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into two categories, "temperature sensation" and "thermal comfort." Although several studies have investigated regional differences in temperature sensation, less is known about the sensitivity differences in thermal comfort for the various body regions. In the present study, we examined regional differences in temperature-related sensations with special attention to thermal comfort. Healthy male subjects sitting in an environment of mild heat or cold were locally cooled or warmed with water-perfused stimulators. Areas stimulated were the face, chest, abdomen, and thigh. Temperature sensation and thermal comfort of the stimulated areas were reported by the subjects, as was whole body thermal comfort. During mild heat exposure, facial cooling was most comfortable and facial warming was most uncomfortable. On the other hand, during mild cold exposure, neither warming nor cooling of the face had a major effect. The chest and abdomen had characteristics opposite to those of the face. Local warming of the chest and abdomen did produce a strong comfort sensation during whole body cold exposure. The thermal comfort seen in this study suggests that if given the chance, humans would preferentially cool the head in the heat, and they would maintain the warmth of the trunk areas in the cold. The qualitative differences seen in thermal comfort for the various areas cannot be explained solely by the density or properties of the peripheral thermal receptors and thus must reflect processing mechanisms in the central nervous system.
We investigated the effects of menstrual cycle phase on thermal sensation, thermal pleasantness, and autonomic thermoregulatory responses during mild cold exposure. Eight healthy young women participated. Experiments were conducted in the follicular and luteal phases: 120 min exposure at 23.5 °C after 40-min at a baseline temperature of 29 °C. Body core temperature was higher (P = 0.01) in the luteal phase than in the follicular phase. Thermal sensation of the whole body (P = 0.59), hands (P = 0.46), and toes (P = 0.94), and thermal pleasantness of the whole body (P = 0.79) were no different between phases. In both phases, mean skin temperature decreased (P = 0.00) in the same manner without any change in metabolic rate (P = 0.90). These results suggest the change of body core temperature in the menstrual cycle phases has no effect on thermal perception of cold or on autonomic cold-defense response.
The aim of this study was to determine whether estrogen modulates central and peripheral responses to cold in female rats. In ovariectomized female rats with and without administered estrogen [E(2) (+) and E(2) (-), respectively], the counts of cFos-immunoreactive cells in the medial preoptic nucleus (MPO) and dorsomedial hypothalamic nucleus (DMH) in the hypothalamus were greater in the E(2) (+) rats than in the E(2) (-) rats at 5 degrees C. Examination of the response of normal female rats to exposure to 5 degrees C at different phases of the estrus cycle revealed that counts of cFos-immunoreactive cells in the MPO, DMH, and posterior hypothalamus and the level of uncoupling protein 1 mRNA in the brown adipose tissues were greater in the proestrus phase than on day 1 of the diestrus phase. This result was linked to the level of plasma estrogen. The body temperature during cold exposure was higher in the E(2) (+) rats than in the E(2) (-) rats and was also higher in the proestrus phase than on day 1 of the diestrus phase. We conclude that estrogen may affect central and peripheral responses involved in thermoregulation in the cold.
: We report a new system for monitoring sensations of many body parts as well as comprehensively showing the distribution of overall skin temperature (T sk ) and temperature-related sensations. The system consists of a console with 52 levers to report temperaturerelated sensations and software that facilitates the visualization of the distribution of T sk and temperature-related sensations by displaying them on a model of the human body. The system's utility was demonstrated with a physiological experiment involving three males and three females. They were exposed to step changes of ambient temperature from 23°C to 33°C. We measured T sk at 50 points, and the subjects concurrently provided estimates of local temperature sensation and thermal comfort/discomfort at 25 loci. This system greatly facilitates the perception and analysis of spatial relationships and differences in temperature and sensation in various areas of the body.Key words: temperature sensation, thermal comfort/discomfort, regional thermal sensitivity.Sensations evoked by thermal stimulation (temperaturerelated sensations) can be divided into two categories, "temperature sensation" and "thermal comfort/discomfort" [1]. Temperature sensations are used to obtain information concerning the thermal condition of external objects or the environment and are evoked by signals from warm and cold receptors in the skin. Thermal comfort/discomfort is important for body temperature regulation because it drives an individual to search for the appropriate thermal environment to maintain normal body temperature. Thermal comfort/discomfort is affected by the thermal state of not only the skin, but also the body core [2]. We can discern local as well as whole body sensations for both temperature sensation and thermal comfort/discomfort [1]. Understanding how the sensitivities of temperature-related sensations differ among body regions is valuable from a physiological point of view and also as a guide for the design of a comfortable environment and efficient clothes and for the provision of optimal medical and nursing care. Several studies have investigated regional sensitivity, but only for temperature sensation [3][4][5][6]. Little is known about regional differences in thermal comfort/discomfort [7,8].To estimate the thermal state of the body surface, we generally measured the skin temperature (T sk ) from a limited number of points (usually less than 10) and averaged them to get a mean skin temperature (mean T sk ). However, to investigate detailed regional sensitivity in temperaturerelated sensations, we found that a more global assessment of T sk is necessary. Although infrared thermography is commonly used for this purpose, it has limitations: e.g., it cannot detect the T sk of areas that are covered with clothes or that do not directly face the camera. A multipoint measurement of sensations is also required to clarify the regional sensitivity of temperature-related sensations. Although verbal reporting is typically used to measure temperature-rela...
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