Mieko Ohsuga

Assessment of phasic work stress using autonomic indices

The present paper concerns the assessment of phasic work stress using autonomic indices such as skin temperature, respiratory measures, and heart rate, blood pressure, and their variabilities. A physiological model of the autonomic regulation of the cardiovascular and respiratory systems is also introduced in order to simulate and interpret the changes in these indices. Two experiments were conducted to investigate high tension and monotony as two types of mental work stress. A tracking task was used to induce high-tension work stress with and without an instruction intended to induce additional emotional stress. The same tracking task was repeated 12 times to simulate monotonous work stress. Fifty healthy adults participated in each experiment. Many physiological measures showed task-dependent changes in the high-tension experiment and at the beginning of the monotonous stress condition. These changes were explained by sympathetic activation, parasympathetic withdrawal, and respiratory rate activation. An additional drop in skin temperature and an additional HR increase were caused by the stressful instruction, which may reflect an emotional strain and can be explained by sympathetic activation. Furthermore, the mid-frequency component (approx. 0.1 Hz) of respiration and respiratory instability showed an obvious increase during the course of the monotonous stress experiment, which may reflect boredom and disgust. It was concluded that multidimensional recordings of autonomic measures that can be obtained during work without extra load on the worker would be helpful to assess different types of phasic work stress. The proposed model was further shown to be able to detect periods of stress in a complex work environment.

Using the Bedside Wellness System During Chemotherapy Decreases Fatigue and Emesis in Cancer Patients

Background: The bedside wellness system (BSW) is effective for decreasing stress and improving mental well-being and should help relieve the side effects and mental disorders of patients during cancer chemotherapy. Methods: The study was a randomized clinical trial. After giving informed consent, patients were randomly assigned to the BSW intervention or control groups. The patients were given the Hospital Anxiety and Depression Scale (HADS) test before the trial to evaluate their emotional baseline. The Cancer Fatigue Scale, which was developed at our institute, and face visual analog scale were used to measure the emotional state and subjective feelings before and after the trial. The degree of emesis was measured using a visual analogue scale after the experience. We set up the system in a room in the outpatient clinic of the National Cancer Center New Hospital Building. Results: The decreases in the fatigue score and emesis score 3–5 days after chemotherapy were statistically significant (both p < 0.05) and carry-over effects were detected. Conclusions: BSW intervention therapy is an effective way to treat fatigue and emesis. This virtual reality system is a new therapeutic method that can be used in palliative medicine.

Entrainment of two coupled van der pol oscillators by an external oscillation

A system composed of two coupled internal oscillators and an external oscillation is studied as a model of biological control systems. The type of interaction between the internal oscillators is a mutual and dissipative one. Three macroscopic states of the internal oscillators are demonstrated in the absence of the external oscillation. Strict and loose entrainment regions of the internal oscillators by the external oscillation are shown in respect to the intensity of the mutual interaction, the intrinsic frequency difference of the internal oscillations, and the magnitude and frequency of the external oscillation. On the other hand, an idea of “holonic system” is introduced and the fundamental properties of the model as a holonic system are elucidated.

Assessment of mental workload based on the model of autonomic regulations on cardiovascular system

For the purpose of the quantitative assessment of mental workload using autonomic indices, a physiological model of autonomic regulations on the cardiovascular system is investigated. The model proposed by H. Luczak (see Biological Cybernetics, vol. 18, p. 1-13, 1975) is selected and studied comparing to experimental data and adding some modifications. The present paper also concerns a method for estimating the parameters of the autonomic system which are influenced by mental workload using a neural network trained by the backpropagation method for data sets obtained by the model simulation.

Towards an effective subjective measurement method based on fuzzy set theory

Conclusions Though further study is still needed to examine the score values obtained from different methods, the consistency of subjective judgments, and the system usability, it is possible to conclude from the above results that these computerized fuzzy rating methods can be quite effective for subjective assessments. Because of the ability of FCRS to use ordinary verbal expressions at the assessment stage, we are now trying to add voice input capability to the system which is expected to improve the constraints on judgments under working situations.

Assessment of mental workload based on a model of autonomie regulations on the cardiovascular system

Quantitative assessment of mental workload (MWL) is helpful in improving the usability of computer systems, the working environment, and work schedule management. We have been investigating the changes in autonomic indices such as heart rate, blood pressure and their variabilities induced by MWL. We found that the multidimensional use of these indices is useful to assess MWL. However, most of the indices are multiply regulated by the autonomic nervous system and influenced by other indices through feedback loops. So if careful considerations are not made, their changes which are not induced directly by MWL would be misunderstood. For that reason, we introduced a physiological model of autonomic regulations on the cardiovascular and respiratory systems to obtain new measures more directly related to MWL, such as sympathetic tone, vagal tone and baroreflex gains.