We have developed a film-type proximity sensor by applying a new duplex silver-ink printing technique to a film substrate. The sensor is a capacitance type, with two electrodes sandwiching the film. By changing the electrode size, the electric lines of force can be extended spatially. If the sensor is approached, a part of the electric lines of force is obstructed by human bodies. This results in a decrease in capacitance, and therefore, it works as a proximity sensor. Because this sensor is very thin and lightweight, it can be easily attached to multiple locations such as the back of a table, chair, or bed, without being found. In this study, we placed it behind a Japanese tatami, and could successfully detect periodic breathing of human lying on it without contacting the body. Such an imperceptible sensor could contribute to ease examinees' discomfort during their health condition monitoring or medical check.
Electrical Impedance Tomography (EIT) is a technique to perform dynamic lung tomography by measuring the electrical impedance. Recently, EIT has been applied in clinical settings, and its usefulness in confirmation of treatment for Acute Respiratory Distress Syndrome (ARDS) and titration of mechanical ventilator setting has been revealed. However, there are no EIT machines commercially available in Japan and also currently available machines have limitations in using in emergency situation and longer use. We are currently developing a machine that is small sized wearable and can be used for a longer period. We would like to discuss the possibility of clinical use especially in emergency and critical care field by showing some cases.
A body shape estimation belt had been developed. The belt was designed for EIT and shape measurement simply. Sixteen channels of curvature sensors and wirings had been integrated into a thin flexible circuit board. The size of the belt was 935 * 58 * 0.34 mm. Total length and weight included measurement circuit was 1,005 mm and approx. 200g respectively. The system could estimate a shape at 50 frames/s in real-time. A basic performance was evaluated by estimating shapes of subset ')' and number '6' in real-time. Curvature sensors showed linear correlation with high correlation coefficient as R=0.998 at maximum. And shapes of subset ')' and number '6' had been estimated well. These results showed that the developed shape estimation belt had a basic performance and feasible for many clinical and healthcare applications.
The specific health check-up has been commenced since 2008, and a measurement of waist circumference became a required item in Japan. However, the waist circumference is not adequate for identifying the accumulation of visceral fat. Therefore, the more selectively measurable radiation-free device was expected to be developed. Thus, we developed a 4-electrodes belt-type visceral fat measuring device, and marketed in 2014 as a medical device. The visceral fat area measured by the device indicated strong correlation (R=0.85 - 0.93) with that estimated by X-ray CT scan image. However, we are developing a visceral fat meter using not only bio-impedance but also abdominal outline shape obtained by shape sensors attached on the belt to improve the measuring accuracy. On the other side, we are attempting to develop a 64-electrodes abdominal fat imaging device using electrical impedance tomography expecting the abdominal image become a strong motivator for behavior modification.
By abdominal circumferences measurements, possibility of metabolic syndrome can be estimated. However to accurately measure abdominal fat, other expensive methods are necessary (e.g. CT scan or MRI). To measure one's visceral fat accurately and overcome this issue, a method to measure one's abdomen accurately and non-invasively, electrical impedance tomography (EIT) for measuring the abdominal area has been proposed. However EIT uses electrodes which contact with human skin, which to be treated carefully. In this report, non-contact method to measure permittivity of abdomen using microwave is proposed. The penetrate wave guide method is applied on large size rectangular wave guide to measure permittivity of human abdomen. Numerical simulations of this method is performed on several kind of layered cylinders which emulate human abdomen. As a result, different scattering coefficients are obtained for each condition. For the future, from measured permittivity, amount of abdominal fat might be estimated.
It is strongly awaited to integrate biological research findings into mathematical models for understanding the dynamic mechanisms underlying the homeostasis of the internal environment. In my research area, a variety of mathematical models of the cardiac functions have been extensively developed at different levels from cells to organs or even up to system levels. Such models are useful in predicting biological responses of the cardiac tissue to various pathophysiological interventions, the drug effects, and developing a new strategy for disease treatment. To further develop this line of research, it is essential to encourage collaborations among mathematical, engineering and medical sciences researchers. This symposium aims at promoting mutual understanding and collaborations among different disciplines and related scientists.
In order to investigate the physiological role of HCN4, a major subunit of pacemaker current of sinoatrial node (SAN), we generated two lines of transgenic mice; HCN4+/ tetA_TRE overexpressing HCN4 at their physiological locus (tTA) ; HCN4Luc/tetA_TRE, a double knock-in mouse that enables complete knockdown of HCN4 expression with doxycycline (TET-off). In vivo, TET-off mouse showed significant bradycardia with intermittent sinus pause or irregular beat, whereas the heart rate of tTA was similar to that of wild type (WT). When we stimulated parasympathetic nerve, WT and tTA equally showed bradycardia. In contrast, complete sinus pause was induced in TET-off. We next recorded action potential of SAN, and found unstable spontaneous firing in TET-off. Application of acetylcholine completely stopped spontaneous firing, and set the membrane potential at stable level. In tTA, this level was more depolarized. These findings indicate that HCN4 may act as a limiter for parasympathetic hyperpolarization of SAN.
Our research group have been conducting simulation studies for analyzing arrhythmia such as sick sinus syndrome, atrial fibrillation, ventricular tachycardia and fibrillation using multi-scale heart models with personal computer and supercomputer. One purpose of our simulation studies is to stratify the arrhythmic risk non-invasively using computer simulation. Recent study has shown that conduction delay around the right ventricular outflow tract is one of the mechanisms to induce ventricular arrhythmias such as Brugada syndrome. Our findings from computer simulation suggest that our model may be useful to stratify the arrhythmic risk in the Brugada syndrome. In this symposium, we will present our simulation scheme and recent progresses. In addition, we would like to discuss our future prospect and the possibility of computer simulation.
What makes the heart beat? This has been one of the fundamental questions of researchers in the field of cardiac physiology. In electrophysiology, cardiac pacemaker cells are characterized as cardiomyocytes possessing automaticity, which is caused by the slow diastolic depolarization toward a threshold potential. Our simplified action potential model, in which the cell is represented as an electrical equivalent circuit consisting of conductances, batteries and a capacitor, greatly facilitates understanding of the basic mechanisms underlying characteristic behavior of the cardiomyocytes and explains automaticity in the pacemaker cell as the transition of the instantaneous equilibrium potential of the membrane capacitor. Possibilities of using simplified mathematical models in parallel with realistic models for deeper understanding of cell functions will be discussed.
Circulatory system is a complicated system, which is finely tuned to maintain adequate blood supply to the cells. For the comprehensive understanding of the system, it is necessary to develop integrative models that are based on detailed cell models. Pathologies at the cellular level propagate to the organ and impair cardiac functions. Conversely, failure of the circulatory system harm normal healthy cells and damage the organ function. These mutual interactions could only be understood quantitatively by using multi-scale simulation models. In the presentation, such multi-scale models will be introduced to discuss utility of the models in the field of biomedical engineering for the further investigation of the circulatory system.
ラマン散乱分光法は分子や結晶格子の振動を検出できるため、生体分子から無機結晶まで様々な材料の分析に活用されてきた。しかし、その発生効率の低さのため、ラマン散乱測定には数秒の露光時間が必要となり、多くの測定を繰り返す画像計測には、ラマン散乱の応用は進んでいなかった。近年になって高出力レーザーや高感度かつ低ノイズな2次元検出器が登場し、ラマン散乱による分光画像計測が比較的容易になり、応用研究が進みはじめた。我々のグループでは、試料上の多数の点から同時にラマン散乱スペクトルを計測するスリット走査型ラマン散乱顕微鏡を開発し、数分から数十分の時間で高解像度のラマン散乱像を得ることに成功した。開発した顕微鏡を用いて細胞内のcytochrome cをラマン散乱により特異的に検出可能なことを示し、アポトーシスにおけるcytochrome c 動態の無標識観察に応用した。また、骨芽細胞、筋芽細胞、およびES細胞の分化状態をラマン散乱スペクトルおよびその空間分布で示すことが可能であることを示した。さらに、ラマン散乱で特異的に観察可能なラマンタグイメージング法を開発し、従来の蛍光法では観察が困難な塩基、脂質等の小分子の観察が可能であることを示した。講演では、ラマン散乱観察の高速化の原理、および上記の応用研究に加え、空間分解能のさらなる向上、およびラマン散乱観察の広視野化についても紹介する。
Raman microscopy is regarded as a powerful tool of biological imaging based on molecular vibrational signatures, providing us with a way for accessing to what has been difficult to see with previous analysis techniques. Among several techniques of Raman microscopy, stimulated Raman scattering (SRS) microscopy allows for high-speed Raman imaging with high sensitivity. We have recently developed a high-speed spectral imaging system with SRS, where Raman images are taken at a video rate (30 frames/s), while the vibrational frequency is changed in a frame-by-frame manner. This system is useful for wide-field imaging as well as imaging of moving samples without motion artifacts. I'll introduce our recent applications of SRS microscopy to imaging of tissues and cell metabolites.
Distinguishing the cell state can be realized by various cell biological techniques, however, these techniques usually require labeling or disruption of cells. Raman spectrum from cell contains various information regarding the cell's ingredient such as molecular species, their amounts and locations. Because these information reflect the state of the cell, Raman spectrum from the cell can be used for predicting the cell state. Here we describe the concept of the use of Raman spectrum as a fingerprint of the cell state, and demonstrate the capability of the method by discriminating the cell type and identifying the differentiation status of cell lines by Raman spectrum from these cells. Because Raman measurement can be performed in non-invasive manner without labeling at single cell resolution, this method can be applied to various applications.
Today image-guided surgery has undergone a great expansion as recent advances of imaging have allowed surgeons to perform more complex procedures with increased safety. However, probes labeling particular molecules can be potentially harmful to the human body. Recent developments in laser techniques have enabled us to visualize functional molecules not only in cultured cells but also in living organ. In spite of the limitations, such as poor light penetration into the deeper area, laser toxicity, and undesirable staining, the in vivo optical imaging technique appears to be an extremely valuable tool for integrated study of diseases. Our aim is to develop the optical technologies for the precise detection of malignant and ischemic lesions. They include label-free molecular imaging by Raman scattering for nerve-sparing surgery and myocardial viability assessment. These technologies can potentially further the diagnostic power of for neoplastic lesions of human tissues in the near future.
Medical Optics and dynamic light-scattering are basic theory of Near infrared spectroscopy (NIRS) for living tissue. Light propagation is described by optical diffusion equations. The equation has two parameters, diffusion coefficient and absorption coefficient. The Lambert-Beer law is used for Spectroscopy. Spectroscopy measures optical density and calculates concentration.The actual NIRS system is based on the modified Lambert-Beer law.We should know the specifications of the device in order to apply to functional research of the brain.
With the increasing distribution of its commercial systems, the functional near-infrared spectroscopy (fNIRS) has been considered as a functional neuroimaging technique of applicable for non-restraining subjects. Most users, however, have not been well informed the relatively important methodological issues as the follows: 1) The signal fluctuation through the scalp blood flow change evoked by the subject's motion, posture change, and also task execution. 2) Extremely low sensitivity for brain tissues other than the most superficial cerebral cortex. 3) More strong relation of BOLD signal in fMRI with the change in deoxygenated hemoglobin than that in oxygenated hemoglobin. This talk aims to empirically show and call attention to such inconvenient points in the practical fNIRS measurements, and to introduce some our technical developments for overcoming them.
In the measurement techniques of cortical activity by using the functional near-infrared spectroscopy (fNIRS), the differences between resting state and task-performing state is often evaluated. However, the experimental conditions of resting state are not controlled. In this study, we investigated the effects of the low-passed dynamic random-dot patterns (LPDRDs) on the resting-state activities. We measured fNIRS signals from prefrontal cortex (PFC) and right-lateral temporal cortex (rLTC) during a block design paradigms, which is constructed of resting-state block with a LPDRD or a fixation crosshair (FT) after performing a 3-back task. We compared which condition is to be recovered to resting-state earlier after brain activation by the task. The results suggest that the average activity of PFC in the LPDRD condition was significantly lower than in the FT condition, indicating that gazing at the LPDRD in resting-state could be attenuated cortical activity more efficiently.
The f-NIRS is becoming widespread by progress in cost reduction, downsizing, and portability of the measuring equipment. On the other hand, in several research reports, we can easily find a lack of uniformity in using and the fact that each of the experimenter proceeded in one's own way. Thus, we verified how those differences affect to results in the sense of reconfirmation about various measurement conditions and methods that are common-sense in the f-NIRS measurement; for example, a time length of a rest for a task, a presence or absence of binding the cables of probes, and so on. And we conducted comparative evaluation of the results due to formal or informal analysis methods. With reporting their results, we felt about necessity of a certain rules and proficiency skills in the use of f-NIRS.
Near infrared spectroscopy has fewer restrictions and lower electric noises than other brain function measurement methods such as EEG or MEG. Therefore, a measurement is easy and it is possible to measure the reaction of various kinds of tasks. However, the influence of changes in the cerebral blood flow often appears as an artifact on NIRS. In addition, the contribution ratio in each case of artifacts is unidentified. In this paper, we propose a technique to reduce or to eliminate the artifact by using the difference between the observed signal and artifact which is calculated by polynomial approximation. We tried to apply a polynomial approximation from the fourth to the sixth. As a result of the experiment, we confirmed that the artifact was reduced by our proposed technique, because the ripple content of differential signal closed to that of background signal.
Recent experimental studies have shown that alterations in subcellular Na channel expression might be involved in Brugada syndrome (BrS). We present with a theoretical model of phase-2 reentry (P2R), which has considered to trigger lethal arrhythmias in BrS. We conducted computer simulations of AP propagation in a myofiber model, where myocytes were electrically coupled with both gap junctional mechanism and electric field mechanism, which is an interference effect between membrane potentials in the intercalated discs, and investigated relations between the spatial and subcellular expressions of Na channels and P2R. No proarrhythmic changes in the AP propagation were observed in the myofiber with the spatial heterogeneity of Na channels. However, the alteration in Na channel expression at the subcellular level as well as the spatially-heterogeneous Na channel expression could induce P2R. Alterations in Na channel expression within myocytes might be responsible for the triggering of lethal arrhythmias in BrS.
Spiral wave is a recognized cause of tachycardia. Tracking the spiral core is essential for understanding the spiral wave dynamics. Previously, identification method of the core was suggested, which detects the core as a phase singularity (PS) in a phase map. A quantitative technique to identify PS in an optical mapping image was also suggested. However, because of a large number of errors, it was still difficult to track the core automatically.
In this study, we suggest a new analysis method of spiral wave. The method quantifies the spatial variance in a phase map. In this phase variance map, the spiral core appears as the peak of phase variance distribution. Using this method, we evaluated the trajectory of the spiral core after point electric stimuli were applied. As a result, we found a correlation between stimulation condition and the spiral wave shift.
Backgrounds: The mechanisms that maintain persistent atrial fibrillation (PtAF) are incompletely understood. We hypothesized that PtAF were maintained by 3-dimensional (3-D) atrial scroll waves (SWs) anchored in regions of large spatial gradients in wall thickness. Methods and Results: We made optical mapping simultaneously from endocardium and epicardium of the left atrium in Langendorff-perfused PtAF (lasting 21.3±11.9 days, n=8) sheep hearts under increased atrial pressure (12 cmH2O). In PtAF hearts, 3-D SW filaments seemed to span the LA wall from endocardium to epicardium. Numerical simulations using 3-D atrial geometries predicted that, similar to experiments, filaments of meandering atrial SWs stabilized at locations with large spatial gradients in myocardial wall thickness. Furthermore, simulations predicted that ionic remodeling and heterogeneous distribution of stretch-mediated channel conductances contributed to filament stabilization. Conclusions: The heterogeneous wall thickness, stretch together with AF-induced ionic remodeling, are the main factors allowing atrial SW and PtAF maintenance.
Effectiveness of electrogram-based ablation for chronic atrial fibrillation (CAF) is still controversial.
Methods: To develop a new approach to driver ablation, we recently developed a novel online rapid CAF visualization system (ExTRa Mapping), and conducted catheter ablation in 15 CAF patients.
Results: (1) ExTRa Mapping demonstrated no stationary rotors. Instead, regions with passive activations and/or non-passive activations (multiple wavelets and meandering rotors) were observed. (2) ExTRa-guided ablation targeting non-passive activations terminated the CAF or reduced the CAF inducibility.
Conclusion: The ExTRa Mapping could open a new avenue for CAF ablation.
Magnetoencephalography (MEG) is a noninvasive neuroimaging technique that provides a measure of cortical neural activity on a millisecond time scale. Recently, we researched the auditory system in young children using custom child-sized MEG in which sensors were located as close to the whole brain as possible for optimal recording in young children. This new device enables us to record brain bilateral function even in young children. The earliest cortical component of the auditory evoked field (i.e., the P1m) is a prominent component in 1- to 10-year-old children. P1m in young children is thought to be a physiological indicator of language acquisition and cerebral laterality. Using the child-customized MEG device, we demonstrated that the children with autism spectrum disorder (ASD) exhibited an atypical development pattern in P1m. Our results contribute to our understanding of diversified pathophysiological mechanisms in the central nervous systems in young children with ASD.
Lifespan is a dynamic process with remarkable changes in brain structure and function. Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. The present study investigated age-related structural brain changes from infancy to early adulthood in healthy individuals, considering sex and brain hemisphere differences. These findings indicated that brain developmental trajectories differ depending on brain region, sex, and brain hemisphere.
We investigated the neural mechanism of the selective listening with the coherence function between a sound envelope and MEG signals. The results showed the coherence values of the noticed sound became higher than the unnoticed sound and their distribution was different between both hemispheres of the brain depending on sound lateralization. In addition, the voice sound showed comparatively high conference values in the left hemisphere regardless of the sound source direction. By using this analysis method, we plan to develop a BCI system to support a hearing ability.
Experiments of participants living in an unusual environment tell us an adaptive mechanism of multisensory integration that could be a key to improve cybersickness. As less attempts have been made to examine adaptation to unusual audition as compared with unusual vision, we developed left-right reversed stereophonic audition using wearable devices and asked participants to wear them continuously for about a month. Psychophysical experiments using the ventriloquism effect showed perceptual reversals of audiovisual spatial integration. Moreover, MEG responses under the audiovisual matching task revealed two steps of adaptation: early adaptation occurring in superior temporal sulcus presumably related to perception and late adaptation occurring in auditory cortex presumably related to behavior. We conclude that these non-linear processes of adaptation achieve optimization of audiovisual spatial integration.
To date, auditory neural systems have been thought to be sensitive to rapid change of sensory input, thus the long-lasting sustained activities after the transient activities responding to sound onset has been ignored. In this study, we targeted rat auditory cortex and attempted to reveal that the sustained activities represent not only sound frequency, but sound-associated emotion and sound texture. A microelectrode array with 96 recording sites recorded sound-responding local field potentials from the auditory cortex of anesthetized rats, and we calculated phase locking values (PLVs). First, machine learning demonstrated that PLV patterns represent the sound frequency tonotopically. Second, not appetitive, but aversive classical conditioning strengthened PLV in the specific band. Lastly, texture of the chord, e.g., consonant/dissonant chord and major/minor chord, differently affected PLV. These results suggest that the sustained activities may strongly contribute to further analysis of the sound in the auditory cortex.
Converging evidence suggests that cortical processing is performed in a hierarchical manner. In the primate object vision, visual information is thought to be processed along the sequence of areas. We identified the direct physiological evidence for the cortical hierarchical processing as propagating activity patterns by employing electrocorticography (ECoG) in monkey, which enable us to record neural activity from wide cortical areas at high spatiotemporal resolution. Quantification of the propagating wave by symbolic local transfer entropy (SLTE) revealed both feed-forward and feedback components. We also found that SLTE topography changed during the visual stimulation. We also examined hierarchal nature of the process by comparing the ECoG activity pattern with the output from each layer of a deep neural network model. The output explained the specific spatiotemporal aspect of the ECoG activity. These results add the physiological insights of the hierarchical processing in the ventral visual stream.
Movement directional tuning is a hallmark that characterizes the response properties of neurons in the motor-related areas found in single-unit recording studies of monkeys. This study attempted to estimate the width of directional tuning from scalp EEG signals in humans by combining of Mobile Brain/Body Imaging (MoBI) and computational modeling. First, a computational model of population of spiking neurons suggests that the width of directional tuning may be estimated from temporal correlations of simulated EEG signals, provided that responses of model neurons are temporally heterogeneous. Then, neural activities and body movements were monitored with high-density EEG and motion capture while subjects made center-out reaching movements toward one of eight targets separated by 45 degrees. As predicted by computational modeling, EEG source dipoles exhibited directional tuning with various tuning widths. MoBI combined with computational modeling provides a noninvasive alternative for understanding neural mechanisms that have hitherto required invasive recordings in animals.
Surgery is an effective treatment for intractable temporal lobe epilepsy where the seizure cannot be controlled by medication. Intractable epilepsy is treated by removing epileptic foci and propagation paths. In surgery, it is important to determine epileptic foci and propagation paths. In this report, we propose a new method to visualize the connectivity among the channels of electrocorticogram(ECoG). The connectivity strength is defined as linear combination of the maximum correlation value and its delay time between channels of ECoG. Then, we estimated the propagation structure of patients with intractable epilepsy using minimum spanning tree whose edge length was connectivity strength. We estimated propagation structure of epileptiform discharges from two ECoG who patients of intractable temporal lobe epilepsy using the connectivity analysis. The results show the same medical opinion obtained by PET analysis. Therefore the proposed method is considered an effective analysis method as a diagnostic indicator of objective evidence.
Waking during nocturnal sleep (WS) is gaining attention in the health science field. Although some findings, (e.g., the power-law distribution of the wake duration time) have been reported, the mechanism of it is still unclear. In this talk, we light on this issue. In a previous study, we showed that corticothalamic feedback loop strength (c2), estimated by an EEG analysis method, clearly tracks the wake-to-sleep transition just before nocturnal sleep. This time, we applied this method to nocturnal sleep. The c2-distribution (n = 52) during nocturnal sleep exhibited clear bimodal, which can be well approximated by superposition of two Gaussian distributions corresponding to sleep (Non-REM 1-4 and REM) and wake states, respectively. This observation suggests that the dynamical change of c2 obeys the Ornstein-Uhlenbeck process in each state. Based on these findings, we show an attempt for stochastic process modeling of WS.
Noninvasive methods for probing direction-selective neuronal activity are effective for understanding human motion perception. Some previous works using the Steady-state Visual Evoked Potential has used adaptation to reveal direction-specific activity. Here we present a method that reveals motion mechanisms directly through a signature predicted by the motion energy model: motion energy detectors produce opposite-signed responses to phi and reverse-phi stimuli.
Recent studies suggest that the resting-state network (RSN) of human brain has close relationship with neurological and psychiatric diseases. So far, mouse has been used to study the mechanism and treatment of these diseases because of applicability of various experimental methods including genetic engineering. Since the fMRI, which has been mainly used to estimate the human RSN, is not suitable for mouse due to insufficient spatial resolution, optical intrinsic signal imaging (OISI) method is being tested on behalf of fMRI. However, it remains many problems including the cost and complexity of experimental system and analytical methods. To solve the problems, we developed a method to analyze RSN of the mouse neocortex by using single-wavelength transcranial OISI method. By using the method, we found that the structure of RSN of mice during REM sleep is significantly different from that during quiescent awake and non-REM sleep.
It is investigated whether or not the spike trains of auditory nerve fiber (ANF) models in response to pulsatile electric stimuli can be modeled as an inhomogeneous Poisson process using computer simulations. Inhomogeneous Poisson process is one of the random point processes for modeling highly localized events, like the spike firings observed in neurophysiology experiments, and the temporal processes can be characterized by the parameterized intensity function. In this study, the intensity function is assumed to be expressed as a series of von Mises distribution with a periodic time interval, so as to capture quasi-periodic spike firings of ANF models in response to sinusoidally modulated pulsatile electric stimuli. The results of computer simulations suggest that the maximum likelihood estimates of the parameters for von Mises distribution and of the spike firing rates can represent the characteristics of the intensity function in inhomogeneous Poisson process.
This study proposes to utilize diurnal change in beat to beat heart rate series and alternans ratio percentile (ARP) for the risk assessment of sudden cardiac death (SCD). These two parameters are obtained by Holter cardiogram. The advantages to utilize risk indices from Holter recordings are twofold: firstly, the data are recorded in natural daily activity, i.e. not stressful compared to lab examination, long term recordings may have more chances to detect abnormality compared to conventional short term ECG recordings. Subjects are divided into three groups, i.e. SCD high risk (SCD-H), low-risk (SCD-L) and control (CTL). The number of cases are 11, 14 and 25 respectively. Combining two indices, serial correlation coefficient between RR and QT intervals and APR, resulted in sensitivity and specificity both above 0.8 except for sensitivity of SCD-H group. Classification accuracy is promising if the SCD-H detection sensitivity will be improved by introducing additional indices.
In recent years, there have been many bed-ridden people because of Cerebral accidents for elderly people in Japan. Almost of them have problem of their joints, which is known for contracture. In this condition, they cannot move their hand's fingers smoothly. If the symptom occurs for the hand's fingers, patients have difficulties to live independently. Then, physical therapists (PT) take an important part in improvement and prevention for the patient's disability. However, PT has to do rehabilitation training multiple times in a day. Accordingly, they not have much time to train many patients. For these reasons, patients cannot get appropriate training when they need. Therefore, this study was made to develop the contracture prevention device for the finger joints. In this paper, we described the prototype for index finger of our device. It consists from cam and link mechanisms by using a DC motor. Furthermore, we examined extension degree and force exerted to finger joints. For these experiments, we indicated this prototype can extend the index finger joints automatically and transitivity.
This study verifies an evaluation index of fall experience using dual-task walk and concept of working memory model. Two kinds of recall problem were given to 70 healthy elderly people during level ground walking. Eighteen subjects experienced fall within past one year. Stride length of every step is estimated using tiptoe mounted inertial sensor. Relation between Stride length and difficulty of induced question is investigated. The experimental results show that an attention coefficient for walk of fall experienced subjects were significantly smaller than that of fall unexperienced one.
Resin is the common material for upper limb prosthesis socket due to their ease and smoothness of forming curved surface to fit the residual limb shape. These socket are suitable for suspension and force transmission, however, the breathability and moisture permeability are low. To understand and moderate the inner socket hydrothermal characteristic of the upper limb prosthesis, it should be measured during operation. However, the measurement is not stable and non-uniform at such condition. Therefore, the objective is set to investigate the temperature and humidity inside the socket with non-amputee subject donning quasi-transradial prosthesis under lower limbs exercise condition. The experiment was conducted on 3 subjects donning socket during exercise using a bicycle ergometer under constant environmental temperature and humidity. As a result, the inner socket body surface temperature showed different characteristic then the resting condition and declined for the initial 8 minutes of the exercise and turned to increase.
We developed a system to measure foot force, acceleration and angular velocity in gait. Then we achieved the outputs by using seven force sensors and six-axis inertial sensor for each shoe. In the experiment, we analyzed gait of three normal subjects by using the proposed system. An analysis method consists of three steps. First, we specified walking cycle from the value of the acceleration. Second, we calculated the excursion of ankle joint by integrating the angular velocity. Third, we specified foremost point and hindmost point of gravity center in walking cycle from the seven force sensors and we calculated anteroposterior distance of gravity center. Analysis objects were excursion of ankle joint and anteroposterior distance of gravity center. We experimented a stride length of the subjects as 3 patterns of 10 cm, 50 cm, and 100 cm. As a tendency, the ankle excursion was small when the stride was small.
Heat and humidity are the major complaints related to the discomfort and termination of the upper limb prosthesis's usage. To propose a better design of prosthesis, basic understanding of the heat transfer mechanism from the limb to the socket is required. In this research, the thermal-cardiac relation of donning myoelectric controlled upper limb prosthesis was investigated by measuring and comparing the conditions of muscle contraction at 3 muscle activity levels: none, mild(MVC 20 %) and high(MVC 70 %). To examine the physiological response of the limb donning the plastic quasi-transradial prosthetic socket, myoelectric potential, inner-socket contact pressure, upper limb venous flow speed, cubital fossa cutaneous blood flow, and inner-socket body surface temperature at the palm and forearm were measured from 3 non-amputee subjects' forearm at selected condition: last 100 seconds of the measurement period for non-exercise condition and initial 100 second of the post exercise period for exercise condition. As a result, the mean body surface temperature increase of the 3 subjects were 1.79, 0.93, and 0.72 deg. C., while the cutaneous blood flow decreased 1.41, 1.81, and 0.12 ml/min/100g when donning the socket, respectively.
We have been developing upper limb orthosis that incorporates two motors to support the movement of arm of the Erb's paralysis patients. The orthosis supports flexion of shoulder and elbow and medial rotation of upper arm independently. Trial experiments were performed by five healthy subjects. Eleven activities of daily living (ADLs) were tested by three methods: without orthosis, with orthosis without medial rotation function, and with the function. From the results evaluated by the visual analog scale (VAS), difficulty of the movement increased with the orthosis and decreased in several ADLs when the orthosis is used with medial rotation function as compared to that without the function.
The purpose of this study is the development of safe and compact handy type haptic device. Conventional haptic device is constituted by motor and link. For this reason, it is difficult to miniaturize. Furthermore, when a system hangs up, that device has the danger which applies unusually large force on a user. Then, we considered applying the EAM to the haptic device. In the previous study, we have developed the rotary and linear type of brake which used the EAM. Applying them, we made a prototype handheld haptic device. That device can generate horizontal resistance force by the rotation type EAM brake and vertical resistance force by the linear type EAM brake.
Japan has increased the elderly and physically handicapped. Elderly and physically handicapped A.D.L.(Activities of Daily Living) is reduced. Improvement of Elderly and physically handicapped A.D.L. is problem. In improvement of A.D.L., we were focused on the support of walking. Walker is mobility device on daily basis. But there are accidents caused by overturn as a problem of walker. This study was made to develop overturn prevention device to walker. First, to establish an index for determining the overturn. We measured locus of body (angle of joint), Speed of walker, Force acting on walker, Positional to walker and user, and other relevant factors. And we examine the correlation between the elements, and establish index for determining the overturn.