Prolonged monotonous driving may lower a driver's awareness level as well as increasing their stress level due to the compulsion to maintain safe driving, which may result in an increased risk of a traffic accident. There is therefore an opportunity for technological assessment of driver physiological status to be applied in-car, hopefully reducing the incidence of potentially dangerous situations. As part of our long-term aim to develop such a system, we describe here the investigation of differential skin temperature measurement as a possible marker of a driver's stress level. In this study, after giving informed consent 25 healthy male (n = 18) & female (n = 7) subjects (26.8 ± 8.0 S.D. yrs) were investigated under environment-controlled conditions, whilst being subjected to simulated monotonous travel at constant speed on a test-course. We acquired physiological variables, including facial skin temperature which consists of truncal and peripheral skin temperatures (Ts) using thermography, beat-by-beat blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), and normalized pulse volume (NPV) used as an indicator of local peripheral vascular tone. We then investigated the driver's reactivity in terms of skin temperatures with this background of cardiovascular haemodynamics. We found that the simulated monotonous driving produced a gradual drop in peripheral Ts following the driving stress, which, through interpretation of the TPR and NPV recordings, could be explained by peripheral sympathetic activation. On the other hand, the truncal Ts was not influenced by the stress. These findings lead us to suggest that truncal-peripheral differential Ts could be used as a possible index indicative of the driver's stress. In fact, a significant correlation was confirmed between stress reference of BP and differential skin temperatures.
Previous studies suggest that body weight support treadmill training is effective to improve walking ability for incomplete spinal cord injuries. However, the moving of a patient's legs during the treadmill training represents ergonomically unfavorable and tiring work for therapists. Therefore, the purpose of this study is to develop a body weight support treadmill training system. This system consists of three parts, powered orthosis, equipment of body weight support and treadmill. The part of powered orthosis is based on Hip-Knee-Ankle-Foot orthosis with trunk support and is driven by pneumatic Mckibben actuator. Pneumatic Mckibben actuator is safe to use, obtains high power and contributes to lose weight of the orthosis. In this study, we try to develop a feedback control system which referred difference between inner pressures of actuators set up an antagonistic arrangement and joint angle of the orthosis. This control method is able to increase stiffness of hip and knee joints of the orthosis and achieves large torque for the orthosis walking. Additionally, co-contraction of pneumatic Mckibben actuators which set up an antagonistic arrangement as bi-articular muscle is able to increase stiffness of both hip and knee joints of the orthosis.
It is well-known that the autonomic nervous system responds in different manners by inducing various emotions. Therefore, we have studied on the responses in human blood circulation evoked by emotional stimuli. In our previous studies, we found different correlations between some parameters of blood circulation with different emotions. These features could be detected more clearly by considering the lag time between the parameters that conducted from the blood circulation control system. Generally speaking, heart rate will increase in an exciting emotion. But this accepted concept was not always true in our previous studies and in some other literatures. Therefore, we developed and discussed the analysis technique for the index of the excitation by focusing on respiratory sinus arrhythmia (RSA) which suggested as the index of rest levels of the cardiopulmonary system. In an exciting state, RSA is expected to decrease because of increasing the demand of oxygen. To find the feature of changes in blood circulation, we measured temporal changes in consecutive blood pressure, ECG and respiratory wave during the emotion of fear, excitation, disgust and sadness, respectively. Each minimum coefficient of cross-correlation between heart rate variability in RSA frequency range and the respiratory wave was sought with considering “the time shift” as a lag time. Consequently, the time series of minimum cross-correlation coefficients varied significantly in an exciting emotion from rest. But, whether the time shift that obtained from the minimum value of cross-correlation coefficients between the parameters could be considered as a lag time of the parameters is open to dispute, we discussed it and obtained reasonable results.
A disadvantage of laparoscopic surgery is the narrow operative field provided by the endoscope camera. This paper proposes the Bird-View Camera System, which is capable of providing a wider view of the internal organs during laparoscopic surgery. This system consists of a camera unit for capturing the image of the inside of the body and a monitor for indicating the capture image to surgeon. With the use of this system, the invasiveness of the procedure is not increased and the specification of current laparoscopic surgery is maintained. Furthermore, it can function as a second camera (in addition to the one attached to the endoscope) and can help assess the overall state of the target area. In this paper, we discuss a newly developed camera unit, which is intended for use along with the proposed system. The camera unit is composed of a miniature color CMOS camera (height: 9 mm) . an indwelling needle, and an extra-thin connector (outer diameter: 1.1 mm) . The specific design of the camera unit and the method for positioning it are shown. The performance of the camera unit has been confirmed through basic and animal experiments.
In this study, we investigated whether psychological states in an environment with visual stimuli can be modeled by physiological indices. As visual stimuli, films to elicit various types of emotions were presented. First, psychological ratings in response to these stimuli were investigated using semantic differential scales. Principal component analysis for the psychological ratings confirmed two primary components, which could be interpreted as the valence and arousal dimensions reported in previous studies. Then, while viewing these stimuli, psychological ratings and multiple central (electroencephalogram (EEG) and near-infrared spectroscopy (NIRS) ) and peripheral (heart rate (HR), skin potential level (SPL), respiration, thermogram, plethysmogram, and eye blinks) physiological activities were measured. Stepwise regression analyses revealed that the psychological valence could be accounted for by indices of the EEG, NIRS and HR. Psychological arousal was also explained by activities of the EEG and SPL. These results suggest that the psychological states in the visual stimulus environment could be modeled by the physiological indices.
(OBJECTIVE) Recent psycho-physiological studies have revealed close relationships between human mental stress and secretion of hormones and/or immunological substances. However, a precise elaboration of fluctuations in the secretion of these biomarkers in the time series against stress is not yet clearly illuminated. In this study, we used Chromogranin A (CgA) as a possible biomarker of mental stress for 1) illustrating the precise stress-response in the time series, and 2) investigating a congruity of CgA as the biomarker for mental workloads. (METHOD) In the experiment, ten male university students were inscribed to conduct a simple and easy arithmetic task (T) for 36 minutes with intermission (I) in two different T/I schedule: (A) a set of 18 (T)-9 (I) was repeated 2 times and (B) a set of 6 (T)-3 (I) was repeated 6 times. It should be noted that the total task period and intermission period is the same in both experiment A and B. (RESULT) As a developing result, salivary CgA concentration depicted an increase during the tasks and decrease (recovering) during the intermissions, while such a change was significant and more remarkable in the experiment A. The difference in the rate of increase/decrease induced by the task/intermission was also observed. (CONCLUSION) The stress-response of CgA in the time series plausibly demonstrated the possible candidacy of CgA as a biomarker for a short-term mental workload. In addition such a difference in the increase/decrease rate or time-lag in the responses by loading/unloading of the mental stress would bring forth an apparent difference in observation, thus impairing the effectiveness of CgA as a stress marker, if the assessment of CgA were not close enough.
In this study, techniques to measure EEG and fMRI simultaneously were investigated, from which P300 responses evoked by visual stimuli were examined. Event-related analysis was applied to combine high temporal resolution of EEG with high spatial resolution of fMRI, which may allow estimation of the temporal change of activation of multiple cortical areas. A time scheme of stimulus presentation and MRI scan was designed, considering the temporal delay between the generation of P300 potential and the BOLD response. Three pattern oddball paradigm using standard, target and novel letter stimuli was performed, in which subjects responded to the rare target-letters but not to frequent standard-and rare novel-letters. Noises arising from MR scan and cardio-ballistic artifacts were removed from the raw data of EEG by subtraction of the time-averaged waveforms of those artifacts. Comparing the grand average response of EEG evoked by target events with that evoked by standard events, a significant difference was found in latency range from 280 to 450 ms (P < 0.001). This enlarged response to the target corresponded to the late component, i. e., P3b, of P300. In the group study of BOLD responses, significant activation appeared in the occipital region, the parietal and temporal regions and the prefrontal cortex, some of which showed a laterality of right-hemisphere dominance. Based on the results of EEG topography during the period of P3b response, a temporal progression of the activations from the occipital visual cortex, via the temporoparietal and temporal regions to the prefrontal cortex was estimated.
This research is aimed to monitor physiological signals obtained by intra-corporeal continuous monitoring. In order to measure the cystometrography in a continuous and non-invasive way, a capsule telemeter prototype equipped with bellows for bladder pressure measuring, and enabled to transmit wirelessly by magnetic coupling has been designed. Such device has been validated by in-vivo experiments with small animals to observe their behavior, which revealed that the heartbeat and pulse wave acoustic signals are also superimposed in the bladder pressure signal. They can be isolated from the original pressure signal by appropriate filtering and amplification process. It has been proved that our sensor-telemetry-system can continuously observe cystometrography and heart rate in real-time. This system is expected to be expanded to cover the heart sound signal or the fetal heart sound signal coming from uterus next to the bladder.
The purposes of this study are to investigate the effect of the elastic energy of the crural muscle-tendon complex on sprint performance and evaluate the function of sprint spike shoes. For these purposes, subjects performed a planter flexion jump (PFJ), a counter movement jump (CMJ), and a drop jump (DJ) using a slider seat system developed in this study, while wearing the several spike shoes. According to the results, in wearing spike shoes having high plate elasticity the relationship between the using ratio of the elastic energy and the increasing ratio of the mechanical power was positive in DJ. Furthermore, the relationship between the forces added the foot joint toward the frontal-horizontal axis in wearing the above-mentioned spike shoes and that in bare foot was positive. These results suggest that the using ratio of the elastic energy in high density counter movement was dependent on an increase of the mechanical power in the foot joint which resulted from wearing spike shoes having high plate elasticity and was, however, related to the sport injury occurrence.