Kiyoyuki Yamazaki

The proposal of the digital plethysmograph using a sensor network

We develop a new digital plethysmograph using a sensor network. We can utilize autonomic indices for instance heart rate and heart rate variability from the plethysmogram recording. It makes possible to evaluate users physiological state easily and on real time.

The hyper hospital-virtual reality based medical system on the computer network-its concept and user-configurable virtual world creating system

We have been developing a novel medical care system which is constructed on an electronic or computerized information network using virtual reality as the principal human interface. The major purpose of the hyper hospital is to restore humane interactions between patients and various medical caretakers by making a much closer contact between them in the real medical scene than that in current conventional medical practice. In the present study, we discuss the most fundamental part of the development of the virtual reality system for the medical use, that is, system software for the creation of the virtual world which can be defined and modified by users of various levels, not only by the medical caretakers, but particularly by patients.

Physiological and psychological assessment of the hyper arousal utilizing a card sorting task

In order to assess psychophysiological state of the hyper arousal, pulse transit time during a mental task was analyzed using the ECG R-wave finger plethysmogram onset asynchrony (RPA) measurement. As the mental task, the authors used the Wisconsin card sorting test (WCST). In the test, the following two kinds of condition were used: (1) a toy balloon burst setting with time limit, and (2) a narrated Japanese novel comprehension test. Under experimental conditions, measured RPAs were shorter than these in control conditions. It is suggested that the RPA is a possible tool for the assessment of hyper arousal through the autonomic responses.

A Fundamental Study Toward Development of a New Brain Computer Interface Using a Checker-Board Pattern Reversal Stimulation

The purpose of this study is to investigate the spectral changes of electroencephalogram (EEG) toward development of a new Brain Computer Interface (BCI) for disabled people with verbal communication disorders such as Amyotrophic Lateral Sclerosis (ALS). In this study, an experiment using EEG recordings was carried out in nine healthy adult volunteers. Periodically reversing checker-board stimuli with two kinds of frequencies (5, 15 Hz) were used to observe users’ selective attention from EEG spectral changes. The stimuli were displayed in two different ways, independently displayed and simultaneously displayed, on the LCD of a personal computer. Volunteers were instructed to attend either 5, 15 Hz or neither of the reversing stimulus during EEG recordings. Obtained EEG data were analyzed by FFT and those power spectra were calculated. As a result, two different frequencies reversal stimuli generated peak of EEG spectrum with attended stimulus frequency. However, the peak generated by 5 Hz stimulus was somehow bigger than that of 15 Hz stimulus due to individual differences. To obtain the comparable height of EEG spectral peaks, the compensate procedure to reduce the sensitivity difference between the two frequencies for each person is required. From a comparison of the EEG power spectral structures, subjective binary decision (5 or 15 Hz reversal stimuli) could be discriminated objectively. Utilizing this phenomenon, EEG based BCI for subjective selection extraction can be constructed. Some problems of feasibility of this method as a BCI were also discussed.

Automatic analysis of EEG and behavior records of rats using an FFT

For animal studies with psychotropic drugs, such as sleep-inducer, fundamental data for establishing the characteristics of a standard state of EEG is essential. In this study, statistical analysis using rat biometric system MUPREMS was utilized and polygraphic measurements were carried out over a 24 hour period. Since visually operated classification of recorded data takes a long time, an automated computer analysis system for rat EEG was developed using FFT. EEG, ECG, EMG and EOG were measured from three Wistar rats. Infrared video recordings were also carried out. Four stages from the video recording, six stages from biomedical recordings were defined to determine the sleep stage and wakefulness. Outputs were compared with the classification results of the visual inspection. As a result, this method was comparable to visual classification. The future problem is also found for the state integration such contextual characteristics on the time axis with the behavior data.

Virtual reality technology as human interface to networked medical system- Its general construction, user reconfigurable design, new cybernetic interface, feasibility, and safety features

Publisher Summary This chapter discusses the general construction, user reconfigurable design, new cybernetic interface, feasibility, and safety features of virtual reality technology as a human interface to networked medical systems. The prototype of the Hyper Hospital described in this chapter has shown that the user reconfigurable virtual reality (VR) world paradigm can be implemented into such a system and can be practically used for this purpose. Two series based on the studies of safety features of virtual reality technologies were carried out. In the first series, 20 healthy young male subjects, and in the second series 10 such subjects underwent the psychological interviews in the virtual space using the virtual reality system for a relatively short duration. Several measures of the physiological, biochemical, neurological, and psychological fatigue are measured before, during, and after the interview session. However, there were no significant changes in the measured objective parameters of fatigue. The features of the user reconfigurable virtual reality world creation as shown in the present study are thought to be very useful. The VR technology is shown to be a potentially powerful tool for the improvement of modern medical care.

Evaluation of the safety features of a virtual reality system

Publisher Summary This chapter discusses the evaluation of the safety features of a virtual reality (VR) system. Several measures of the physiological, biochemical, neurological, and psychological fatigue are calculated before, during, and after the control experiments. Similar is the case with the VR loading experiments in the study discussed in the chapter. It is found that there is subjective fatigue, particularly related with the psychological condition. The urinary catecholamine release (including epinephrine and dopamine) is found to increase in the VR loading sessions as well as the control video sessions. No increase in the norepinephrine release in the VR experiments are found while it increased in the control video session. Based on this, it is speculated that the use of VR does not have much effect on the physical condition, but may slightly affect the mental or psychological state; however, the extent of this effect is not as severe as the usual video presentation.