石橋 圭太

Abstract Background There are many conflicting findings on the gaze cueing effect (GCE) of emotional facial expressions. This study aimed to investigate whether an averted gaze, accompanied by a fearful expression of different durations, could enhance attentional orientation, as measured by a participant’s eye movements. Methods Twelve participants (3 females) completed the gaze cue task, reacting to a target location after observing changes in the gaze and expression of a face illustrated on a computer screen. Meanwhile, participants’ eye movements were monitored by electrooculography. The GCE was calculated by reaction time as an indicator of attention shift. Results The analysis of the overall data did not find a significant effect of fearful facial expressions on the GCE. However, analysis of trial data that excluded a participant’s eye movement data showed that brief (0, 100 ms) presentation of the fearful facial expression enhanced the GCE compared to that during a neutral facial expression, although when the presentation time of the fearful expression was increased to 200 or 400 ms, the GCE of the fearful expression was at the same level as when model showed a neutral expression. Conclusions The results suggest that the attention-enhancing effect of gaze cues induced by rapidly presented fearful expressions occurs only when the effect of eye movement trials is excluded. This effect may be mediated by reflexively neural circuits in the amygdala that process threatening stimuli. However, as the expression duration increased, the fearful expression’s attention-enhancing effect decreased. We suggest that future studies on the emotion modulation of GCE should consider the negative effects of participants’ saccades and blinks on the experimental results.

The effect of shape on the memory encoding of color schemes was examined using human-body shapes andrectangles, and N2 posterior contralateral (N2pc) and contralateral delay activity (CDA) were obtained from theevent-related potential during memory encoding. The task involved memorizing a stimulus presented in the left andright visual fields. The N2pc amplitude was largest when rectangular color schemes were memorized and the humanbodyshapes were distractors. No significant difference was found in the CDA amplitude between the shapes. Theseresults suggested that the memory of the color schemes was affected by selective attention rather than sustainedattention.

This study examined the human shape's effects on the visual working memory for color schemes in a recognitiontask using event related potential (ERP). The experiment confirmed which parts condition (body region, geometricfigure) and layout condition (human, disordered) affected the color memory. Regardless of the parts condition,color schemes with human layouts were more correctly memorized. Similarly, the P3 amplitude of ERP in the parietalregions, which decreases with the memory load, were significantly larger in figures with human layouts, regardless ofthe parts. These results suggest that the layout has a major impact on color scheme memory.

Postural changes impair the ability of the cerebrovasculature to buffer against dynamic pressure fluctuations, but the mechanisms underlying this impairment have not been elucidated. We hypothesized that autoregulatory impairment may reflect the impact of static central volume shifts on hemodynamic factors other than arterial pressure (AP). In 14 young volunteers, we assessed the relation of fluctuations in cerebral blood flow (CBF) to those in AP, cardiac output, and CO2, during oscillatory lower body pressure (LBP) (± 20 mmHg at 0.01 and 0.06 Hz) at three static levels (- 20, 0, and +20 mmHg). Static and dynamic changes in AP, cardiac output, and CO2 explained over 70% of the variation in CBF fluctuations. However, their contributions were different across frequencies and levels: dynamic AP changes explained a substantial proportion of the variation in faster CBF fluctuations (partial R2 = 0.75, standardized β = 0.83, P &lt 0.01), whereas those in CO2 explained the largest portion of the variation in slow fluctuations (partial R2 = 0.43, β = 0.51, P &lt 0.01). There was, however, a major contribution of slow dynamic AP changes during negative (β = 0.43) but not neutral (β = 0.05) or positive (β = - 0.07) LBP. This highlights the differences in contributions of systemic variables to dynamic and static autoregulation and has important implications for understanding orthostatic intolerance.

Background: Time perception associated with durations from 1 s to several minutes involves activity in the right posterior parietal cortex (rPPC). It is unclear whether altering the activity of the rPPC affects an individual's timing performance. Here, we investigated the human timing performance under the application of transcranial direct-current stimulation (tDCS) that altered the neural activities of the rPPC. Methods: We measured the participants' duration-discrimination threshold by administering a behavioral task during the tDCS application. The tDCS conditions consisted of anodal, cathodal, and sham conditions. The electrodes were placed over the P4 position (10-20 system) and on the left supraorbital forehead. On each task trial, the participant observed two visual stimuli and indicated which was longer. The amount of difference between the two stimulus durations was varied repeatedly throughout the trials according to the participant's responses. The correct answer rate of the trials was calculated for each amount of difference, and the minimum amount with the correct answer rate exceeding 75% was selected as the threshold. The data were analyzed by a linear mixed-effects models procedure. Results: Nineteen volunteers participated in the experiment. We excluded three participants from the analysis: two who reported extreme sleepiness while performing the task and one who could recognize the sham condition correctly with confidence. Our analysis of the 16 participants' data showed that the average value of the thresholds observed under the cathodal condition was lower than that of the sham condition. This suggests that inhibition of the rPPC leads to an improvement in temporal discrimination performance, resulting in improved timing performance. Conclusions: In the present study, we found a new effect that cathodal tDCS over the rPPC enhances temporal discrimination performance. In terms of the existence of anodal/cathodal tDCS effects on human timing performance, the results were consistent with a previous study that investigated temporal reproduction performance during tDCS application. However, the results of the current study further indicated that cathodal tDCS over the rPPC increases accuracy of observed time duration rather than inducing an overestimation as a previous study reported.

BACKGROUND: Sinusoidal lower body negative pressure (SLBNP) has been used to investigate the cardiovascular response to slow periodic changes in blood shifts, but measurements of slow fluctuations take a long time if measured for each period of SLBNP separately. Our study aimed to investigate whether the cardiovascular responses to superimposed SLBNP (S-SLBNP), which is expected to reduce the measurement time, are different from responses measured individually. METHODS: S-SLBNP was configured by superimposing two conventional SLBNPs (C-SLBNP) at 180-s and 30-s periods in the pressure range from 0 to -25 mmHg. As the S-SLBNP has double the static load of C-SLBNP, we also used offset SLBNP (O-SLBNP), which has the same static load level as S-SLBNP. Heart rate (HR), thoracic impedance (Z(0)), and mean arterial pressure (MAP) were measured from 11 male subjects. The transfer functions of gains from MAP to HR (Gain-HR/MAP) and from Z(0) to HR (Gain-HR/Z(0)) were calculated as indexes of arterial baroreflex and cardiopulmonary baroreflex regulation of HR, respectively. RESULTS: The Gain-HR/MAP in the 180-s period (2.11 +/- 0.17 bpm/mmHg; mean +/- SEM) was larger than that of the 30-s period (1.04 +/- 0.09 bpm/mmHg); however, there was no significant difference between the SLBNP conditions. The Gain-HR/Z(0) in C-SLBNP (9.37 +/- 1.47 bpm/ohm) was smaller than that of the other conditions [18.46 +/- 2.45 bpm/ohm (O-SLBNP); 16.09 +/- 2.29 bpm/ohm (S-SLBNP)]. DISCUSSION: Using S-SLBNP could reduce the measurement time needed to examine the arterial baroreflex. However, the cardiopulmonary baroreflex was modified by the static load of SLBNP.

本研究の主な目的は、円滑性追跡眼球運動における速度知覚に動的視対象の視認性による周辺視野の感度が及ぼす影響を調べることであった。追跡タスクの難易度は、以下の刺激特性による視認性で調節された。背景的特性（格子パターンの色構成：白黒対白グレー）と曲線の太さ（0.06deg、0.18deg、0.36deg）が異なる６種類の比較刺激を用いて実験を行った。PC画面上を正弦波の軌跡を描きながら左から右へ移動する比較刺激の先端点の速度を標準刺激よりも｢遅い」または「速い」と感じたかの二者択一による実験から、PSE（主観的等価点） を導出し、分析を行った。結果、円滑性追跡眼球運動の速度知覚は背景である格子パターンの色構成が白とグレーであるときと、正弦波曲線の太さが太いほど有意に速くなることが確認された。これらの結果から、円滑性追跡眼球運動における速度知覚への周辺視野の影響及び周辺視野の速度知覚の変容効果が難易度によって異なることが確認された。

The present study investigated the association of near-infrared spectroscopy (NIRS) signals with systemic hemodynamic changes (SHCs) that can exert confounding effects on brain function analysis. NIRS and SHC parameters - basal thoracic impedance (Z_0), mean arterial pressure (MAP), total peripheral resistance, cardiac output, heart rate and stroke volume - were measured in 13 male subjects. Periodical SHCs were generated using four different periodical changes in sinusoidal lower body negative pressure (12.86, 18, 30 and 90 sec of 0 to -40 mmHg). The frequency response of gain of NIRS signals against Z_0 showed high-pass filter characteristics, however, that of gain against MAP showed low-pass filter characteristics. These results suggest that a compensatory model of NIRS against SHCs needs to consider the frequency characteristics of cardiovascular regulation.

本研究では、円滑性追跡眼球運動（SP眼球運動）時の速度知覚が背景の視覚情報の影響を受けることについて検討した。具体的には、PC画面上を正弦波の軌跡を描きながら左から右へ移動するテスト刺激の先端点の速度を参照刺激よりも「遅い」または「速い」と感じたかの二者択一による実験から、PSEを導出した。背景の視覚情報として、A：1 cycle per degree（cpd）、背景の視覚情報あり、B：0.25cpd、背景の視覚情報あり、a：1cpd、背景の視覚情報なし、b：0.25cpd、背景の視覚情報なしの4条件を設定した。結果、刺激 Bとb において、背景の周期的な特性（0.25cpd）によって速度知覚が遅く感じられたことが確認された。結果から、視覚情報のあり条件では空間周波数0.25cpd条件の方は1cpdより知覚速度が有意に遅くなり、視覚情報のなし条件では、これらの空間周波数条件間に有意な差がないことが示唆された。

This topic summarizes a viewpoint from which to approach the physiological polytypism of orthostatic cardiovascular regulation, which is an important system in biped animals for adapting the gravitational blood shift to the lower body. Physiological polytypism is one of the keywords in physiological anthropology and is closely related to the belief that variation does not result from error but is real. This concept also considers that the ideal individual, who shows all variables in average value in a population, lacks scientific validity. Another keyword, whole body coordination, provides the conceptual framework with which to approach physiological polytypism in order to avoid assuming an ideal individual. The general role of whole body coordination in relation to orthostatic cardiovascular regulation is discussed.

Background: The purpose of the present study was to compare sinusoidal versus constant lower body negative pressure (LBNP) with reference to very mild whole-body heating. Sinusoidal LBNP has a periodic load component (PLC) and a constant load component (CLC) of orthostatic stress, whereas constant LBNP has only a CLC. We tested two sinusoidal patterns (30-s and 180-s periods with 25 mmHg amplitude) of LBNP and a constant LBNP with -25 mmHg in 12 adult male subjects. Results: Although the CLC of all three LBNP conditions were configured with -25 mmHg, the mean arterial pressure (MAP) results showed a significantly large decrease from baseline in the 30-s period condition (P <0.01). In contrast, the other cardiovascular indices (heart rate (HR), stroke volume (SV), cardiac output (CO), basal thoracic impedance (Z(0)), total peripheral resistance (TPR), the natural logarithmic of the HF component (lnHF), and LF/HF (ln (LF/HF))) of heart rate variability (HRV) showed relatively small variations from baseline in the 30-s period condition (P <0.01). The result of the gain and phase of transfer function at the sinusoidal period of LBNP showed that the very mild whole-body heating augmented the orthostatic responses. Conclusion: These results revealed that the effect of the CLC of LBNP on cardiovascular adjustability was attenuated by the addition of the PLC to LBNP. Based on the results of suppressed HRV response from baseline in the 30-s period condition, we suggest that the attenuation may be caused by the suppression of the vagal responsiveness to LBNP.

This study investigated the physiological function of suppressed melatonin through thermoregulation in a cold environment. Interactions between thermoregulation directly affected by exposure to a cold environment and indirectly affected by endogenous melatonin suppression by bright-light exposure were examined. Ten male subjects were exposed to two different illumination intensities (30 and 5000 lux) for 4.5 h, and two different ambient temperatures (15 and 27 degrees C) for 2 h before sleep under dark and thermoneutral conditions. Salivary melatonin level was suppressed by bright light (p < 0.001), although the ambient temperature condition had no significant effect on melatonin. During sleep, significant effects of pre-sleep exposure to a cold ambient temperature (p < 0.001) and bright light (p < 0.01) on rectal temperature (T(re)) were observed. Pre-sleep, bright-light exposure led to an attenuated fall in T(re) during sleep. Moreover, T(re) dropped more precipitously after cold exposure than thermoneutral conditions (cold: -0.54 +/- 0.07 degrees C/ h; thermoneutral: -0.16 +/- 0.03 degrees C/h; p < 0.001). Pre-sleep, bright-light exposure delayed the nadir time of T(re) under thermoneutral conditions (p < 0.05), while cold exposure masked the circadian rhythm with a precipitous decrease in T(re). A significant correlation between the T(re) nadir and melatonin level (r = -0.774, p < 0.05) indicated that inter-individual differences with higher melatonin levels lead to a reduction in T(re) after cold exposure. These results suggest that suppressed endogenous melatonin inhibits the downregulation of the body temperature set-point during sleep. (Author correspondence: ishibasi@design.kyushu-u.ac.jp)

There are large inter-individual differences in pupil size and suppression of melatonin by exposure to light. It has been reported that melatonin suppression by exposure to light increases when pupils are pharmacologically dilated. However, the correlation between normal inter-individual difference in pupil size and melatonin suppression by exposure to light is not clear. Twenty-three healthy male subjects (22.6 +/- 2.7 years old) were exposed to light (1000 Ix) for 2 h at night. The starting time of exposure to light was set to the ascending phase of melatonin concentration of each subject. Pupil area and saliva melatonin concentration were measured before exposure to light under dim light (15 Ix) and during exposure to light. There were large inter-individual differences in melatonin suppression and pupil area. The mean and standard deviation of percentage of melatonin suppression 2 h after exposure to light was 57.2 +/- 22.1%. The mean and standard deviation of pupil areas before and 2 h after exposure to light were 30.7 +/- 7.9 mm(2) and 15.9 +/- 4.8 mm(2), respectively. The percentage of melatonin suppression by light was positively correlated with pupil area during light exposure (r = 0.525, p < 0.02). Interestingly, it was also correlated with pupil area measured before exposure to light, under dim light (15 Ix) (r = 0.658, p < 0.001). These results suggest that inter-individual difference in pupil area positively correlates with melatonin suppression by light and that pupil area under dim light is a predictor of inter-individual differences in melatonin suppression by light. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

This study examined the effects of odors on sustained attention during a vigilance task. Two essential oils (lavender and eucalyptus) and two materials (l-menthol and linalyl acetate) were compared with a control. The increase in reaction time was significantly lower with lavender than with the control. The results suggest that the administration of lavender helped to maintain sustained attention during the long-term task.

The purpose of this study was to investigate the effects of 12weeks of physical training on cardiovascular responses to postural change at 27℃ and 35℃. 16 sedentary subjects were assigned to either a training group (n=8:30-min ergometer at 60% V^^・O_2peak, 3 days a week) or a control group (n=8 : no exercise). Measurements were made of heart rate (HR), stroke volume (SV), cardiac index (CI), mean blood pressure (MBP), total peripheral resistance (TPR), rectal temperature (Tr), mean skin temperature (Tsk) and heart rate variability (HRV), before and after a chronic physical training. After training, training group significantly increased their V^^・O_2 peak (+10.3%, p<0.01). As for the cardiovascular responses to head-up tilt, in both group there were significant interaction effects between postural condition and ambient temperature in HR, CI and TPR. In training group, HR was significantly decreased after training during head-up tilt at 27℃. These results suggest that the physical training may effect on cardiovascular responses to postural change.

This experiment tested effects of human eye pigmentation depending on the ethnicity on suppression of nocturnal melatonin secretion by light. Ten healthy Caucasian males with blue, green, or light brown irises (light-eyed Caucasians) and 11 Asian males with dark brown irises (dark-eyed Asians) volunteered to participate in the study. The mean ages of the light-eyed Caucasians and dark-eyed Asians were 26.4 +/- 3.2 and 25.3 +/- 5.7 years, respectively. The subjects were exposed to light (1,000 lux) for 2 h at night. The starting time of exposure was set to 2 h before the time of peak salivary melatonin concentration of each subject, which was determined in a preliminary experiment. Salivary melatonin concentration and pupil size were measured before exposure to light and during exposure to light. The percentage of suppression of melatonin secretion by light was calculated. The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 +/- 4.2%) than in dark-eyed Asians (73.4 +/- 20.0%) (P &lt; 0.01). No significant difference was found between pupil sizes in light-eyed Caucasians and dark-eyed Asians. These results suggest that sensitivity of melatonin to light suppression is influenced by eye pigmentation and/or ethnicity.

Two different spectral analyses of heart rate (HR) variability (HRV) were performed on seven young male subjects to evaluate the effects of different color temperatures of light exposure (6700 K, 5000 K, 3000 K) before sleep on cardiac vagal activity. In investigating HRV, we used an ordinary fast Fourier transform (FFT) and coarse graining spectral analysis (CGSA), which selectively extracts random fractal components from a given time series. The results showed that suppressions of HR during sleep after 6700 K light exposure were more inhibited than the other two lighting conditions. Increases in high-frequency (HF) components of HRV during sleep were also inhibited by 6700 K pre-sleep lighting. These results indicate that pre-sleep exposure to light of a higher color temperature may inhibit the enhancement of cardiac vagal activity during sleep. Moreover, significant HF alterations were shown in fractal-free HF (not in ordinary HF) components by CGSA. Because the HF component originates from respiratory sinus arrhythmia with periodical fluctuations, CGSA may be an appropriate approach for HRV evaluation during sleep.

This study aimed to assess the relationship between basal metabolic rate (BMR) and metabolic heat production, and to clarify the involvement of BMR in determining the phenotype of cold tolerance. Measurements of BMR, maximum oxygen uptake, and cold exposure test were conducted on ten males. In the cold exposure test, rectal (Trec) and mean skin temperatures (T ms), oxygen uptake, and blood flow at forearm (BFarm) were measured during exposure to cold (10°C) for 90min. Significant correlations were observed between BMR and increasing rate of oxygen uptake, as well as between decreasing rate of BFarm and increasing rate of oxygen uptake at the end of cold exposure. These findings suggested that individuals with a lower BMR were required to increase their metabolic heat production during cold exposure, and that those with a higher BMR were able to moderate increased metabolic heat production during cold exposure because they were able to reduce heat loss. This study showed that BMR is an important factor in determining the phenotype of cold tolerance, and that individuals with a low BMR showed calorigenic-type cold adaptation, whereas subjects with a high BMR exhibited adiabatic-type cold adaptation by peripheral vasoconstriction.

This study was carried out to examine the seasonal difference in the magnitude of the suppression of melatonin secretion induced by exposure to light in the late evening. The study was carried out in Akita (39 degrees North, 140 degrees East), in the northern part of Japan, where the duration of sunshine in winter is the shortest. Ten healthy mate university students (mean age: 21.9 +/- 1.2 yrs) volunteered to participate twice in the study in winter (from January to February) and summer (from June to July) 2004. According to Japanese meteorological data, the duration of sunshine in Akita in the winter (50.5 h/month) is approximately one-third of that in summer (159.7 h/ month). Beginning one week prior to the start of the experiment, the level of daily ambient light to which each subject was exposed was recorded every minute using a small light sensor that was attached to the subject&apos;s wrist. In the first experiment, saliva samples were collected every hour over a period of 24 h in a dark experimental room (&lt; 15 lux) to determine peak salivary melatonin concentration. The second experiment was conducted after the first experiment to determine the percentage of melatonin suppression induced by exposure to light. The starting time of exposure to light was set 2 h before the time of peak salivary melatonin concentration detected in the first experiment. The subjects were exposed to light (1000 lux) for 2 h using white fluorescent lamps (4200 K). The percentage of suppression of melatonin by light was calculated on the basis of the melatonin concentration determined before the start of exposure to light. The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6 +/- 18.4%) than summer (37.2 +/- 33.2%), p &lt; 0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter.

The purpose of present study was to observe the differences of thermoregulatory responses between atugari (=susceptible to the heat) and samugari (=susceptible to the cold). The subjects were 12 healthy young Japanese adult women (age: 21.8±1.7yrs, stature: 160.5±7.8cm, weight: 49.6±7.5kg, BMI: 19.2±2.4). They put on shorts, T-shirts and short pants. Exposure periods were evening (E) and morning (M) during follicular phase (F) and luteal phase (L). The climatic chamber was controlled at 24℃ RH50%, the temperature increased to 29℃ over 60 minutes gradually. The subjects kept the sitting position. Measurement items were rectal temperature (Tr), skin temperature and subjective sensations. We determined atugari and samugari according to the subjective sensations during exposure. The main results were as follows. 1) The order of values of Tr and mean skin temperature was L・E>F・E>L・M>F・M. 2) The theromoregulatry responses were more influenced by circadian rhythm than menstrual cycle. 3) The order of skin temperature of hand and foot was E<M. 4) Atugari had a tendency to feel warm in the peripheral area and to feel cool in the body stem area than samugari.

The purposes of the present study were to observe the thermoregulatory responses from view points of sex difference, seasonal difference between winter and summer, and susceptibility to the heat (atugari) and the cold (samugari). The subjects were 13 females (20.5±0.5yrs, 159.2±6.4cm, 52.1±6.9kg) and 16 males (20.8±1.6yrs, 172.8±4.5cm, 61.6±6.3kg). They put on shorts or underpants, T-shirts and short pants. In the evening, the climatic chamber was controlled at 24℃ RH50%, the temperature increased to 29℃ over 60 minutes gradually. The subjects kept the sitting position. Measurement items were oral temperature, skin temperature, body weight, heart rate, blood pressure and subjective sensations. We determined atugari and samugari according to the subjective sensations of whole body during exposure. The main results were as follows. (1) The classification of atugari and samugari by self judgment did not always agree with the results of exposure experiments, (2) The skin temperatures were winter > summer in the body stem area and winter < summer in the peripheral area in male and female. (3) The skin temperatures were male < female in the body stem area and male > female in the limbs area. (4) Males felt warm in winter than in summer, and they felt warm than females in winter. (5) The values of subjective sensation were atugari > samugari generally. We guessed that the evening exposure produced these phenomena.

Variations in cardiovascular responses to orthostatic stress were investigated in terms of physiological polymorphism. Variations of physiological measurements are subdivided into individual differences and measurement errors. However, individual differences are often considered to be an error in statistical analysis due to its limitations in experimental design. In order to discuss about the relative contribution of individual difference in cardiovascular responses to postural changes, percent contribution (PC) was estimated using the Taguchi method. Six healthy male adults (age range: 21-27) were subjected to orthostatic stress by inducing a postural inclination of 60° head-up-tilting to the horizontal, and the responses were measured thrice in each subject on different days. The respective changes of heart rate (HR) and stroke volume (SV) in the period from the resting supine to the head-up-tilt position were significantly increased (p&lt 0.01) and decreased (p&lt 0.01) without affecting the mean blood pressure (MBP). The PC of individual difference in HR showed a significantly higher ratio of individual difference during the head-up-tilt (71.4-76.2%) compared with supine rest (0.0-50.4%). While the main variations of HR during supine rest were not the individual differences between the subjects, the day-to-day differences within the subject were significant. The PC of individual differences in MBP and SV constantly displayed a significant difference between the subjects. These results suggest that the strategy for maintaining stable cardiovascular regulation may be different even in normal subjects. In the perspective of physiological parameters, PC monitoring may serve as an empirical approach to evaluate physiological polymorphism.

The purpose of this study was to determine the relationship between individual difference in melatonin suppression by exposure to light and habitual bedtime. Seventeen healthy male students (mean age: 22.6±2.4yr) volunteered to participate in the study. The subjects were exposed to light (1000 1x) for 2 hours from 2 hours before the time of peak salivary melatonin concentration. Two hours after exposure to the light, melatonin suppression had occurred in fifteen subjects. No significant correlation was found between the rate of melatonin suppression and habitual bedtime in the fifteen subjects in whom melatonin suppression occurred. However, the habitual bedtime of the two subjects in whom melatonin suppression did not occur was earlier than that of the other subjects. These results suggest that there are some people with very low sensitivity to light and that this may affect habitual bedtime.

In the present study, we attempted to clarify the effects of lifestyle and body compositions on basal metabolism and to clarify the effects of physical training on thermoregulatory responses to cold. Basal metabolism, body compositions, and questionnaires regarding lifestyle were evaluated in 37 students. From multiple linear regression analysis, sex, muscle weight, fat intake, and diurnal temperature were selected as significant explanatory variables. In a second experiment, rectal and the skin temperature at 7 different points as well as the oxygen uptake of eight males were measured at 10°C for 90 min before and after training. The decline in rectal temperature that was observed before training was not observed after training. In addition, rectal temperature was significantly higher at post-training than at pre-training. These results suggest that some lifestyle factors affect cold tolerance in particular, daily activity might improve our ability to control heat radiation and basal heat production.

In order to examine whether the spectral compositions of light source may affect sleep quality, sleep architecture under different color temperatures of light sources was evaluated. Seven healthy males were exposed to the light sources of different color temperatures (3000 K, 5000 K and 6700 K) for 6.5 h before sleep. The horizontal illuminance level was kept at 1000 lux. Subjects slept on a bed in near darkness (< 10 lux) after extinguishing the light, and polysomnograms recorded the sleep parameters. In the early phase of the sleep period, the amount of stage-4 sleep (S4-sleep) was significantly attenuated under the higher color temperature of 6700 K compared with the lower color temperature of 3000 K. Present findings suggest that light sources with higher color temperatures may affect sleep quality in a view that S4-sleep period is important for sleep quality.

The non-visual effects of the color temperature of fluorescent lamps were reviewed based mainly on our recent studies with special reference to physiological aspects in humans such as arousal level, autonomic nerve system including heart rate variability, blood pressure and body temperature regulation, and sleep architecture. It was concluded that there obviously existed the non-visual effects of the spectral composition of fluorescent lamps on physiological aspects, as predicted based on the functions of the nuclei located on the photic non-visual pathway.

ヒトの聴覚の可聴域は、ISO規格では20Hz-20,000Hzとされている。一般的に可聴域の上限(20kHz)を超える高周波数の音は超音波と定義されている。可聴域上限を超える超音波はイルカやこうもり等の生物では重要な情報の伝達や獲得に使われている。気温や光等の物理刺激に対する感受性を数多く有することは環境適応へ有利に働くであろう。ヒトは可聴域上の聞こえないとされる超音波に対して何らかの感受性を有するのであろうか。超音波は潮騒や風の音の中にも含まれるばかりがオフィス内の種々の電化製品からも発生している。超音波がヒトの生理反応にどのような影響を与えるのかを探ることはヒトの環境適応能を探る上でも、また快適なオフィス空間を構築する上でも重要である。超音波に関する生理的研究はMEDLINEなどのデータベースを用いて検索したが、骨伝導による超音波の影響を除くと、大橋らの研究以外は見当たらない。大橋(1997)は、超音波成分を多く含むガムラン音楽を用いて、超音波成分が人体に与える影響を研究した。その結果、ガムラン音楽を呈示することにより、閉眼時において脳波のα波が主に後頭部に増加したことから、超音波を含む音は人間にリラックス効果をもたらすと報告した。

We have already presented two studies of the traditional carrier frame, the seita. In our first study, we reported on seita users supporting loads not on the lumbar vertebrae but on the sacrum. In the second study, we showed that carrying a load on the sacrum was efficient in terms of metabolic rate, muscle activity, cadence and subjective responses. The purpose of this study was to verify the effect of carrying a load on the sacrum in terms of gait pattern. We compared the kinetic parameters produced while carrying a load on the sacrum (LOS) with those produced while carrying a load on the lumbar vertebrae (LOLU). Maximum propulsive force and medial impulse were significantly larger in LOS than in LOLV These results suggested that a normal gait pattern was maintained more in LOS conditions than in LOLU conditions. This indicated that seita-fitting was efficient for carrying and transporting loads.

We investigate the changes in torso body surface with upper limb movement, and employ these data for designing the new tsumeeri uniform. The areas of greatest body surface extension/contraction comprise the shoulders, dorsal area of armpit, and hip/buttock region. Based on these data, proposals are made for changes to shoulder pads, use of retention wire in the shoulders, and changes in the uniform pattern. We next evalute the new prototype by electromyogram and subjective declarations. Regarding shoulder refoems, the former suggested a reducton of muscular burden was achieved in the trapezius muscle and distal regions and the middle deltoides muscle, while the latter reported a significant improvement in tightness and ease of arm movement; i.e., the reforms proved effecyive. Regarding subtle changes in pattern design, while muscle load was reduced in the trapezius muscle and distal regions as well as the anterior deltoides muscle, no significant difference was reported by subjective declaretion.

It has been well known that far infrared rays radiated from ceramics fiber has thermal effect on humans. This study aimed to investigate if the fabric containing the ceramics fiber, with which the seat and back of chair (FIR) was covered, improve the problems of office workers such as neck - shoulder stiffness and cold sensation of the limbs as compared with non-ceramic fiber chair (BLANK). Ten healty male students (22.31±1.1year-old) volunteered for the study. The decrement of skin temperatures of the dorsal hand and foot at FIR was decreased. The activity of frontal muscle kept a resting level at FIR during mental work, but increased at BLANK and the enhancement of arousal level above optimum was also estimated from the increase in the inclination angle of the trunk at BLANK. It was suggested that FIR might keep the arousal level moderate and improve cold sensation of limbs.

健康女子8名を被験者とし,洗髪台使用時の洗髪動作,行動が被援助者に及ぼす影響について仰向けで頭部を軽度上昇させた体位(F位)と椅座前屈位(Z位)で比較検討した.その結果,洗髪行動前後のエネルギー代謝量の増加量および血圧の経時的変化には体位の違いによる有意差を認めなかった.洗髪中の心拍数,LF成分,LF/HF比は両体位とも安静時と比較して高値を示したが,F位は洗髪により心拍数とLF成分が有意に変化し,Z位の場合はその体位を保持するだけで交感神経系優位となり洗髪中と体位保持中間の各自律神経指標の差はわずかであった.又,洗髪行動前後の気分プロフィール検査得点を比較すると,ネガティブな気分は減少し,活気の気分は強まることが示され,中でもF位でのみネガティブな気分に有意な減少を認めた

The purpose of this study was to evaluate the physiological and psychological responses of subjects who had their hair shampooed. Subjects consisted of eight healthy females. Metabolic rate. blood pressure, heart rate and heart rate variability(HRV)were used as physiological indices. Psychological response was assessed using the Profile of Mood States(POMS)before and after the experiment. After resting on a bed for 30 min, the subjects hair was washed in a standardized procedure at a sink in two different positions:in a supine position on a special chair requiring the head to be lifted by 15〜30゜(Position F). and in a sitting position leaning forward over the sink(Position Z). There were no significant differences in metabolic rate and blood pressure between Position F and Z. Heart rate, LF(low frequency)component. and LF/HF(high frequency)ratio derived from HRV during the hair washing were increased compared to pre-washing in both positions. In comparison between washing hair and without washing hair in each position, heart rate and LF component during the hair washing in Position F were significanlty higher than without washing hair in same position. POMS showed that there was a lower score for negative responses, and a higher score for「Vigor」post-washing and drying compared to pre-washing in both position. Above all, significant changes of a score for negative response were observed only in Position F. There were no distinct differences in physiological responses between the two positions. but the psychological results suggested that compared with a shampoo in Position Z. a shampoo in Position F had a positive effect on the mind of the subjects.

A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28°C to 18°C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15°C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.

In this study, we used spectral analysis of heart rate variability (HRV) to estimate the changes in autonomic control in response to disparate stimuli produced by mental task and graded head-up tilting. The low frequency (LF) component of HRV provided a quantitative index of the sympathetic and parasympathetic (vagal) activities controlling the heart rate (HR), while the high frequency (HF) component of HRV provided an index of the vagal tone. We studied 17 healthy male subjects (21-25 yr of age) who were placed on a tilt-table and the graded tilt-protocol involved tilted sine angles 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0. These tilt-protocols were repeated with or without the mental task, which consisted of auditory distinctive reactiontime tasks. The basal autonomic mode against the graded head-up tilt was characterized by reciprocal changes in sympathetic and vagal tones. There were significant increases of HR corresponding to the mental task with lower tilt-angle, albeit the changes with higher tilt angles were not significant. Furthermore, there were increases and decreases of the LF component induced by the mental task at lower and higher tilt-angles, respectively. These results revealed that the different responses of HR and LF component against the same tasks could be derived from the alterations of autonomic mode during gradual changes in autonomic control.

The purpose of this study was to evaluate the cardiac autonomic control over mental task under various ambient temperatures (21°C, 28°C and 35°C). Seven healthy male subjects engaged in the mental tasks, which consisted of distinctive reaction-time tasks. Respiratory coefficient of variation of instantaneous heart rate (CV RESp), derived from the cross-correlation function between heart rate and respiratory curve, was used as a parameter to assess parasympathetic nervous functions. The difference between total coefficient of variation (CV IHR) and CV RESP was used as a parameter to assess sympathetic nervous functions. The mean heart rate increased at high ambient temperature (35°C) and also during mental task. Both the effects of ambient temperature and task conditions were significant on heart rate, and also on CV IHR. Moreover, the effects of ambient temperature and task conditions in CV IHR were divided into the effect of ambient temperature on CV RESp and the effect of task conditions on the difference between C IHR and CV RESP. These results implied that respiratory modulated parasympathetic activity might control basal the effect of ambient temperature, and the other components including sympathetic activity contribute to the increase in heart rate due to mental task.

Heart rate variability (HRV), a non-invasive index of autonomic controls of the heart, has extensively been employed in various fields of study. The application range of this index persists to expand over the research horizon, and the need continues to demand technical complements for hitherto known deficiencies. Concurrent technical advances in recent years have yielded methodological techniques capable of performing quantitative analysis of HRV. However, as various approaches designed for HRV analysis exist, quantitative comparisons of the investigations have become difficult. Current physiological interpretations of the components of HRV are also inconsistent. Moreover, the issue of respiratory control has been much disputed when determining the HRV. In an attempt to clarify the current controversial state in HRV measurement, the present paper, based on the physiological background of HRV, pursued various procedures of HRV measurement and furnished global explanations for special features characterizing the various analytical approaches adopted thereof.