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.
Relevance of decreased cerebral blood flow (CBF) and impaired cognitive function has been pointed out, however, the direct relationship between changes in CBF and cognitive function has not been sufficiently elucidated. The purpose of this study was to determine whether cognitive function would be affected by the acute reductions in CBF in 14 male healthy students. Middle cerebral artery mean blood velocity (MCA V_<mean>) and cognitive function were measured at three conditions; rest (pre), reduced CBF condition (during), and CBF recovery condition (post). The reduction in MCA V_<mean> was elicited by voluntary hyperventilation induced-hypocapnia. Cognitive function was impaired with the reduction in MCA V_<mean>; i.e. reaction time at during hyperventilation condition was significantly longer than those of pre and post conditions (in conflict task; P<0.01). These results suggest that cognitive function may be affected by acute change in MCA V_<mean> by hyperventilation.
To evaluate the effect of two different mattress on sleep in hospitalized patients, we estimated subjective sleep quality and measured objective sleep variables by a sheet-shaped body vibrometer placed under the mattress. The vibrometer can generate almost identical sleep/wake scores to those obtained by wrist actigraphy. Ten hospitalized patients (6 males, 4 females; aged 21-77) were monitored, sleeping in their private room for 6 consecutive nights in the two-period crossover design. The results revealed that sleep on a comfortable mattress in a hypnagogic posture yielded better sleep quality. A better mattress provides better sleep for hospitalized patients.
The purpose of the present study was to investigate university students' knowledge regarding squat exercise. A questionnaire-based survey was administered to students (n = 270) to clarify the relationships between exercise habits, knowledge of squat exercise, and frequency of squat exercise implementation. Squat exercise was reportedly performed by almost all participants, regardless of presence or absence of exercise habits. However, among the participants who exercised regularly, more than 50% did not consciously train their gluteal muscles. Furthermore, of participants who did not exercise regularly, about 70% did not consciously train their gluteal muscles. These results suggest that although squat exercise implementation frequency was high regardless of presence or absence of exercise habits, the squat method might not be properly understood. Therefore, to enhance training benefits, it is important to instruct students regarding the correct way of performing squat exercise.
Cortisol awakening response (CAR) is considered as an index of hypothalamus-pituitary-adrenal (HPA) axis. Some studies have indicated that CAR might be different depending on psychological traits of individuals. The present study investigated relations between CAR and psychological traits in Japanese males. The results showed that there was a negative correlation between CAR and openness trait of "Big five", suggesting that the individuals with high openness are associate with low CAR compared to those with low openness. This inconsistent result with previous studies suggests that cultural factor affects the relation between CAR and psychological traits.
The benefits of grouping increase with group size, but simultaneously so do the costs. Depending on the circumstances, the degree to which costs and benefits vary, and the resultant optimal group size changes. I studied behavioral ecology of male Japanese macaques (Macaca fuscata yakui) and their method of association with groups and managing the costs and benefits associated with group formation. The decision of males to range with other animals depended on the intensity of inter- and within-group competition, their social position, and the reproductive potential of their group. This behavioral flexibility of males with respect to group cohesion contributed to the approach to the optimal group size.
This study adopts a social psychology perspective to explain the scientific approach to "group." Social psychology is a research area examining human behavioral and psychological processes in society based on empirical and scientific approaches. The first section introduces the classical group experiment of social psychology, i.e., conformity, social loafing, and bystander effect. The next section discusses the combined view of physiological anthropology and social psychology from social neuroscience method and evolutionary psychology perspective.
Recent advances in technologies for genomic analysis have led to the discovery of a vast amount of sequence variations in the human genome. The growing list of these genomic variations, largely single nucleotide polymorphisms, is highly useful for the identification of genetic variations underlying the physiological polymorphisms and disease susceptibilities in the present human populations. Moreover, the understanding of variations in the human genome sheds light on the evolution of medical and non-medical traits in modern humans. In the present paper, I review the knowledge obtained from recent studies on the genomic diversity in human populations, especially in terms of medical traits and evolution.
Physiological polytypism is affected by a variety of environmental and genetic factors, and physiological parameters have been observed to vary between different populations and even within population in different environments. In particular, adaptation to cold environments is considered to have played an important role in the survival of Homo sapiens during the last glacial period, and recent studies have suggested that non-shivering thermogenesis in humans played an important role in our recent evolutionary history. This review examined human physiological adaptations to cold, specially the importance of physiological polytypism in non-shivering thermogenesis in humans.
This article provides a historical viewpoint on how human variations have been understood in 19th century. "Homme moyen" ("average man" in English) was an idea advocated by Adolf Quetelet (1796-1874) and was intended as an explanation for why inter-individual variations in human traits follow a normal distribution. His idea has been influential until today although it received much criticism in those days. This idea, however, blurs the distinction between inter- and intra-individual variations in human traits. The discrimination of these two variations is a requisite procedure for studying polymorphism in physiological traits since it generally presents larger intra-individual variations compared with physical traits.
Many physiological and behavioral functions in humans show a near 24-hour (circadian) rhythm in accordance with the rotation of the earth. It is known that there are inter- and intra-individual differences among circadian functions in humans. Chronotype, age and sex are primary factors that mediate the phenotype of individual circadian functions; however, several environmental factors such as the external light-dark cycle also modulate the individual circadian phenotype. Measuring circadian functions should thus provide useful information to establish physiologically optimal conditions in everyday life, but possible confounding factors should be carefully considered.