Masashi Kawasumi

The Role of Toe-gap Force for the Evaluation of Falling Risk on the Elderly

This paper was proposed a toe-gap force measurement to estimate the lower limb muscular power. In the proposed method, the clipping toe-gap force is measured between the great toe and the digitus secundus. The toe-gap force in this situation, is muscles of the lower limb, which are supposed to have roles in the effort against falling. This study was used three experiments to determine whether or not the use of the toe-gap force measurement was useful from a practical viewpoint. First, the aging change in toe-gap force was examined by using the developed measuring device for 361 people included the elderly with physical weakness. Second, to examine the relation between the toe-gap force and falling, we were examined falling experience in a year for 82 healthy volunteers. Third, to examine the relation between muscular power and the toe-gap force, the results of the toe-gap force were compared to the result of the 10 m walking time for 153 healthy volunteers. We found following results: 1. the toe-gap force reflected the lower limb muscular power decrease rapidly from 65 years old. 2. The non-faller group demonstrated the factor of 1.3 greater toe-gap force compared with the faller group. The subjects who have less toe-gap force have experienced many falls. 3. the measured toe-gap force is closely related negative correlation to walking ability. This implies that the lower limb muscular power is reflected on the toe-gap force measurement. It is thus concluded that, the proposed method can be a practically useful method for evaluating quantitatively the lower limb muscular power of the elderly against fall.

Nonstationary EEG Analysis using random-walk model

We suggest an analysing method with random walk model in nonstationary EEG. Short-Time Fourier Transform or Wavelet transform has been used to analyze the EEG, but there is inherent uncertainty between time and frequency resolution. To cope with it, a random walk model with a quasi-parametric function is applied to the nonstationary signal. The scalp EEG is obtained during episodic memory retrieval task. Subject is required to press the button when a word pair remembered is displayed as visual stimuli. The experimental results show that the model order obtained by a random walk model is higher than model order by conventional AIC. Comparing to parameter estimation used model order by AIC, Our suggested method showed that a more realistic parameter estimation is obtained.

Parasympathetic activation enhanced by slow respiration modulates early auditory sensory gating

Sensory gating is a preattentional mechanism to filter irrelevant information from the environment. It is typically reflected as a suppression of the event-related P50 component for successive sounds in the auditory modality. Although stress-induced sympathetic activation has been reported to disrupt P50 suppression, little is known about the modulatory effect of parasympathetic activation on early auditory sensory gating. We determined the parasympathetic effect on the magnetic P50 (P50m) suppression by controlling the respiratory rhythm and recording data simultaneously with magnetoencephalography and electrocardiography, using three successive click sounds as stimulus and ten normal individuals as study participants. The respiratory rhythm was guided by visual cues and set at 0.3, 0.25, or 0.2 Hz for distinct auditory stimulus sequence blocks. Heart rate variability analysis showed that slow respiration leads to significantly large high-frequency power, which is known as the parasympathetic index, whereas low-frequency/high-frequency ratio, known as the sympathetic index, did not differ with the respiratory rhythm. Although P50m suppression was observed in the left and right primary auditory areas for every respiratory condition, the left P50m intensity for the first sound was significantly decreased in the case of slow respiration, thereby indicating disruption of the left P50m suppression. Since background alpha oscillatory power, reflecting the arousal level, was similar for every respiratory rhythm, it is concluded that parasympathetic activation enhanced by slow respiration modulates P50m gating by reducing the initial neural sensitivity for an auditory input. Not only sympathetic but also parasympathetic effects should be considered in the evaluation of P50/P50m biomarkers.

A Fundamental Study on an Input Operation of the Communication Aids by Eyeblink Using Image Analysis Methods - Change of the Feature of an Eyeblink Waveforms Resulting from Attributed to Conscious Actions Accompanying Voluntary Eyeblink -

The input devices for the operation of communication aids and the switches that enable multiple value input are required for disabled at the terminal stage of Amyotrophic Lateral Sclerosis (ALS). We considered the utilization of eyeblink that is relatively less associated with ALS at the terminal stage for the switches. It is known that eyeblink waveforms are different in between voluntary eyeblink and spontaneous eyeblink. Eyeblink waveforms are one-dimensional waveforms obtained by sampling palpebral fissure widths of eye blinking at a constant time interval and by plotting them on a temporal axis. The purpose of this study is to investigate the possibility of categorizing eyeblink data into multiple spaces. We focused on the variations in the shape of eyeblink waveforms attributed to conscious actions accompanying voluntary eyeblink. There was a significant difference in shape feature parameters obtained from eyeblink waveforms between normal voluntary eyeblink and voluntary eyeblink accompanying conscious actions. The results suggest that eyeblink data could be differentiating into six values.

Study of Touch Display in Surrounding Environmental Information Acquisition System for Deaf-blind Persons

Surrounding environmental information on the approach of the person etc. is transmitted to deaf-blind person by the interpreter and caregiver. However, when the interpreter and caregiver leave the side, the deaf-blind person comes not to be able to understand surrounding environmental information and feels insecurity. It is considered that the uneasiness can be reduced by presenting the distance and direction of the others from the deaf-blind person. To reduce this uneasiness, the surrounding environmental information acquisition system is developed in the study. This system is assuming use at home, since deaf-blind person spends a lot of time at home. The system is useful to understand the distance and direction of the others when the interpreter and caregiver are away from the side of deaf-blind person. The information are the direction and the distance from deaf-blind person to the others. The system can present the horizontal directions and the three distances, less than 1m, 1m to 2m, and 2m or more. Deaf-blind person can obtain the information via vibration of solenoid built in the touch display. In this paper, the appropriate shape of display and arrangement of presentation devices in the acquisition system for surrounding environment information for use were examined.

Research of Operation Method of Accessibility Equipment for Severely Handicapped Based on Voluntary Eye Blink

Serious disabled persons with motor disabilities such as amyotrophic lateral sclerosis and progressive speech impairment necessitates the use of an assistive communication aid. However, the disabled also need accessibility equipment to use the aids. This paper describes the research of the input method for the operation of the accessibility equipment, which is used by the serious disabled. The input method is based on electro-oculo-gram (EOG) that is controlled by the disabled. EOG is a technique for recording eye movements and eye blinks through electrodes placed around the eye. If the disabled can create several patterns of EOG waveforms, multiinput method is realized using these differences. We previously reported the technique to identify voluntary eye blink appeared on the EOG. Because voluntary eye blink is simple operation, we investigate the possibilities of utilization of consecutive blinks and gaze. 1) We examined the influences of the consecutive voluntary eye blinks by changing the blink intervals. We revealed that the blinks in interval at 95% when incorporating upward gaze and forward gaze. The results suggest that the incorporation of upward gaze and forward gaze has possibilities of realization of multi-input method.

Evaluation of Lower Limb Function of Age Change by Using Principal Component Estimation

Falling is one of the most common and serious problems because advancing age has been associated with muscle weakness, reduced cutaneous sensation and deterioration of walking ability. We have investigated relation between the fall and lower limb function by development of evolution methods for lower limb function using principal component analysis so far. This paper focuses on change of the value of the evaluation of lower limb function, such as value of walking ability, value of muscle strength of lower limb and value of flexibility of ankle. The subjects were 16 healthy young volunteers (mean ± S.D: 19.9 ± 0.6 years) and 10 healthy aged volunteers (mean ± S.D: 80.6 ± 6.1 years)) living in a special elderly nursing home. All subjects completed the informed consent procedures, and agreed to participate in this study. Measurement items related to lower limb function were selected from the items which we have ever used. Selected measurement items of function of lower are distance of extroversion of the toe, angle of flexion of the toe, maximum width of step, knee elevation, moving distance of greater trochanter, walking balance, toe-gap force and rotation range of ankle joint. The young group demonstrated the factor of 1.6 greater the assessment score of walking ability compared with the aged group. The young group demonstrated the factor of 1.4 greater the assessment score of muscle strength of lower limb compared with the aged group. The young group demonstrated the factor of 1.2 greater the assessment score of flexibility of ankle compared with the aged group. Parameters with significant differences between the elderly group and young group were selected and summarized by principal component analysis into lower ability assessment indices including walking ability and flexibility of ankle. The results suggested that it was possible to assess the lower limb function of aged and young numerically and to advise on their foot function.

Semiparametric approach to Nonstationary Signal Analysis

We suggest a semiparametric approach to analyze nonstationary signal. A Gamma probability density and maximum likelihood is employed to estimate the most model order and model coefficients on the assumption that model parameters are distributed on kernel density estimator with two hyper-paraneters. The innovation noise is no more identically distributed in semiparametric method. The simulated results showed two hyper-parameters alpha=0.15 and beta=0.99 are determined for the most suitable model parameters and had an advantage of both parametric and nonparametric method.

Periodical measurement and evaluation of the ambulatory ability of aged under taking the medical foot care for one year

Many countries are gradually forming the aging society. Social concern is increasing in preventing fall of aged. Since 80% or more of hip fracture of aged were caused by falls, fall is one of the most serious problem in aged. The improvement in aged people’s walking ability is important for QOL, and fall prevention. In order to evaluate the improvement of the walking ability after medical foot care, the rotation range of ankle joint, the knee elevation, the walking balance, and the moving distance of greater trochanter were investigated during the walk. The subjects were 10 healthy volunteers (age range 73–96 years old, mean 80.3±6.0 years old, 3 males and 7 females) living in a special elderly nursing home. The coordinates of markers attached to the subject’s greater trochanter, knee joint, ankle, turberosity of fifth metatarsal bone, and heel were measured using digital camcorder during the walk. The data was analyzed statistically. As a result of performing medical foot care for one year, the rotation range of ankle joint, the knee elevation, and the walking balance during the walk were improved, also the moving of greater trochanter became stabilized. Because the medical foot care, which removes the interference from thickening of the nail, improved the rotation range of ankle joint, the knee elevation, the walking balance and the moving of greater trochanter, it seems that it is effective to improve the walking ability of the aged. It is suggested that the medical foot care of the aged has possibility to prevent the fall.

Nonstationary signal analysis in episodic memory retrieval

The problem of blind source separation from a mixture that has nonstationarity can be seen in signal processing, speech processing, spectral analysis and so on. This study analyzed EEG signal during episodic memory retrieval using ICA and TVAR. This paper proposes a method which combines ICA and TVAR. The signal from the brain not only exhibits the nonstationary behavior, but also contain artifacts. EEG data at the frontal lobe (F3) from the scalp is collected during the episodic memory retrieval task. The method is applied to EEG data for analysis. The artifact (eye movement) is removed by ICA, and a single burst (around 6Hz) is obtained by TVAR, suggesting that the single burst is related to the brain activity during the episodic memory retrieval.