Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

Parkinson's disease (PD) and basal ganglia dysfunction impair movement timing, which leads to gait instability and falls. Parkinsonian gait consists of random, disconnected stride times—rather than the 1/f structure observed in healthy gait—and this randomness of stride times (low fractal scaling) predicts falling. Walking with fixed-tempo Rhythmic Auditory Stimulation (RAS) can improve many aspects of gait timing; however, it lowers fractal scaling (away from healthy 1/f structure) and requires attention. Here we show that interactive rhythmic auditory stimulation reestablishes healthy gait dynamics in PD patients. In the experiment, PD patients and healthy participants walked with a) no auditory stimulation, b) fixed-tempo RAS, and c) interactive rhythmic auditory stimulation. The interactive system used foot sensors and nonlinear oscillators to track and mutually entrain with the human's step timing. Patients consistently synchronized with the interactive system, their fractal scaling returned to levels of healthy participants, and their gait felt more stable to them. Patients and healthy participants rarely synchronized with fixed-tempo RAS, and when they did synchronize their fractal scaling declined from healthy 1/f levels. Five minutes after removing the interactive rhythmic stimulation, the PD patients' gait retained high fractal scaling, suggesting that the interaction stabilized the internal rhythm generating system and reintegrated timing networks. The experiment demonstrates that complex interaction is important in the (re)emergence of 1/f structure in human behavior and that interactive rhythmic auditory stimulation is a promising therapeutic tool for improving gait of PD patients.

DOI： 10.1371/journal.pone.0032600

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

A purpose of this study is to support communication of developmentally disabled individuals with motor paralysis, such as Guillain-Barre Syndrome, brain-stem infarction, having difficulty in conveying their intention. In the present paper, a pointing device controlled by DC-coupled electrooculograms (EOGs) has been developed. The optic angle of the subject was estimated from the amplitude of vertical and horizontal EOGs for determining the two dimensional pointing position on the PC screen in real time. The eye blinking artifact was reduced using a median filter. The displacement of electrode position was compensated by considering the potential gradient. Moreover, the position error caused by drift phenomenon was adjusted by using head movement. The accuracy and operating speed of the proposed method were evaluated in human experiments.

DOI： 10.1541/ieejeiss.129.1792

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Other Link： http://www.jstage.jst.go.jp/article/ieejeiss/129/10/129_10_1792/_pdf

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1038/s41598-024-74526-x

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Other Link： https://www.nature.com/articles/s41598-024-74526-x

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.engappai.2023.106639

Scopus

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Language：Japanese   Publisher：Movement Disorder Society of Japan (MDSJ)  

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41598-022-14070-8

Web of Science

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

This paper describes a highly sensitive microelectromechanical systems (MEMS) accelerometer sensor module to measure micro muscle sounds. Regarding the drift mechanism, we focus on charged particles based on residual water related to MEMS fabrication. Based on temperature programmed desorption (TPD) analysis and electrical experiments, it is clarified that the drift is caused by negatively charged OH− and is suppressed by vacuum packaging. The noise floor can be reduced by the improved sensitivity of the MEMS accelerometer. The developed MEMS accelerometer can realize the sensitivity of 1157.0 fF/G and Brownian noise of 149.0 nG/√Hz. The developed sensor module consisting of the developed MEMS accelerometer and the capacitance to digital converter (CDC) can achieve a noise floor of 26.7 μG/√Hz without any obvious drifts, establishing the target value of less than 50 μG/√Hz. Therefore, it is confirmed that the developed sensor module can detect micro muscle sounds without contracting a muscle in the frequency range of 20–40 Hz.

DOI： 10.35848/1347-4065/ac5b25

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac5b25/pdf

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sii.2015.7405069

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sii.2012.6427372

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In a walking rehabilitation, the cooperative walking between therapist and patient is implemented and the synchrony of walking rhythm is often observed. So, we suggest that the interpersonal synchrony is important for walking rehabilitation. Our group has proposed gait assistive system using interactive rhythmic auditory stimulation to emulate interpersonal synchrony. It is called “Walk-Mate”. In the previous study, the improvement effects of walking with the fixed-tempo Rhythmic Auditory Stimulation (RAS) and Walk-Mate were compared. As a result, walking with Walk-Mate had 1/f structure and was more effective than walking with RAS. In this study, the emulated interpersonal cooperative walking between human and auditory stimulation was analyzed to investigate the relationship between synchrony and gait improvement effect. Fixed-tempo RAS were compared to Walk-Mate. Twenty PD patients and 18 younger healthy persons were participated in experiments. We showed that the phase difference with Walk-Mate was less variable and more temporally-stable than with RAS. It meant the walking with Walk-Mate has the higher synchrony than with RAS. The combination of the result and previous result indicates that the synchrony between participants and auditory stimulation were related to the gait dynamics of participants' stride time. In addition, the PD patients showed the lower synchrony than young healthy people. Therefore, we suggest that it is necessary that the auditory system encourage them to synchronize. We suggested the importance of considering the synchrony in rehabilitation for PD patients.

DOI： 10.1109/sii.2012.6427292

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Previously, research on gait control has mainly focused on interpersonal synchrony and locomotor control. However their intersection, the interpersonal synchronization of stepping rhythms which is widely observed in our daily life, remains relatively unexplored, despite being a common phenomenon that has considerable rehabilitation potential. Therefore, from the perspective of mutual entrainment of gait rhythms, we have constructed an interpersonal synchrony emulation system between a human subject and a biped virtual robot that generates pacing signal cues using nonlinear oscillators. This system synchronizes the stride interval times of a human and the robot in a cross-feedback manner; by presenting auditory stimulation that indicates the timing of the partner's foot contacting the ground. Here, we evaluated the effectiveness of the system in gait stabilization of twenty-one Parkinson's disease (PD) patients, who previously displayed disturbances in rhythm formation and festinating gait (accelerating steps). The results showed that the festinating gait, as measured as stride time reduction rate, significantly stabilized and accelerated less with the system compared to unassisted walking. Additionally, significant carry-over effects were observed. After termination of the auditory stimulation, the gait remained stabilized. Our previous pilot study suggested that the gait of PD patients was dynamically stabilized by applying the inter personal synchrony process between the timing of human's gait and of external auditory cues. In this paper, we showed significant improvement for the festinating gait in twenty one PD patients.

DOI： 10.1109/iccme.2012.6275639

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Parkinson's disease (PD) is a neurodegenerative disorder by degeneration of dopamine neurons, affecting motor controls related to basal ganglia. Because severe movement disorders such as gait disturbances are often observed, evaluation from gait analysis is useful. From such a background, Coefficient of Variation (CV) and Detrended Fluctuation Analysis (DFA) comes to be used as one of the methods for analyzing the variability of the stride interval in recent years. However classification of the severity of PD by stride interval variability has not been reached to practical use enough. In this paper, in order to clarify the difference in age and the severity of PD patients, variability of stride interval were analyzed by CV and DFA. As a first step, we performed analysis of stride interval in three minutes' walk of 17 PD patients, 13 healthy elderly and 12 healthy young people. Particularly, we divided PD patients based on the Hoehn and Yahr (HY) scale into an HY2 group (n=9) and an HY3 group (n=8) in order to examine the relation to disease severity. Results indicate that CV seemed to distinguish PD patients from healthy people and that DFA fractal exponent tended to be related to the age and the disease severity. From these results, gait analysis using both CV and DFA is suggested to classify participants into healthy young, healthy elderly, HY2 and HY3 groups. For future direction, there are possibilities for seeing the progression from healthy people to PD patients.

DOI： 10.1109/iccme.2012.6275643

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Recently, robotics attracts attention in field of not only industry and production but also assistive technology and rehabilitation method. It is required how the system generate assistive functions in interaction with the user, while lots of one-sided help forms are in previous researches. From these backgrounds, we have focused on cooperative gait between humans as interpersonal synchronization, and modeled the mechanism of footstep rhythm synchronization. Moreover, we developed an interpersonal synchrony emulation robot named Walk-Mate, which was biped virtual robot synchronizing with the user's footstep rhythm via walking together. In this study, we evaluated the effect of Walk-Mate in stabilizing gait with Parkinson's disease (PD), which previously displayed disturbances in rhythm formation and festinating gait (accelerating footsteps). The results showed that the festinating gait, evaluated by stride time reduction rate, significantly stabilized and accelerated less with Walk-Mate compared to unassisted walking. Additionally, carry-over effects were significantly observed. After termination of the auditory stimulation, the gait remained stabilized. These suggested that gait with PD was dynamically stabilized by the interpersonal synchrony process between timing of human's gait and of external auditory cues. In this paper, we showed significant improvement for the festinating gait in the PD patients.

DOI： 10.1109/mhs.2012.6492492

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons, affecting motor controls by basal ganglia. Serious movement disorders such as tremor or gait disturbance are often observed, but early diagnosis of PD is difficult. From such a background, Detrended Fluctuation Analysis (DFA) attracts attention as one of the methods for analyzing the fluctuation of the gait cycle in recent years. Therefore, the aim of this study is to clarify the relationship between the fractal exponent of DFA and disease severity of the PD patients. We performed the DFA analysis of gait cycle in 200 meters' walk of 17 PD patients and 12 healthy young people. Particularly, we divided PD patients based on the Hoehn and Yahr (HY) scale into an HY2 group (n=9) and an HY3 group (n=8) in order to examine the relation to disease severity. Results indicate that fractal exponent was significantly lower in both PD groups (HY2, HY3) compared to the young healthy person. Fractal exponent also tended to be lower for the HY3 group compared to the HY2 group, although this tendency for fractal exponent decreasing with the disease severity was not significant here. From these results, the randomness of gait fluctuation seems to related to the severity of PD, suggesting a possibility for diagnosis of PD using fluctuation analysis of gait.

DOI： 10.1109/sii.2011.6147452

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Authorship：Lead author,　Corresponding author   Language：English   Publisher：IEEE  

The purpose of this study was to investigate the influence of interactive and non-interactive rhythmic auditory stimulation (RAS) on gait cycle fluctuation in Parkinson's disease (PD) patients. WalkMate and fixed-tempo RAS were used as interactive and non-interactive RASs that the participants walked with. In the results, 1/f structure of the fluctuation was restored and carry-over effect was shown by interactive RAS, compared to non-interactive RAS. The experiment demonstrated that interaction is important in the (re)emergence of 1/f structure in human behavior and that interactive RAS is a promising therapeutic tool for improving gait of PD patients.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Considerable research attention has been devoted to interpersonal synchrony and to locomotor control. However their intersection, the interpersonal synchronization of stepping rhythms which is widely observed in our daily life, remains relatively unexplored, despite being a common phenomenon that has considerable rehabilitation potential. Therefore, from the perspective of mutual entrainment of gait rhythms, we have constructed an interpersonal synchrony emulation system between a human subject and a virtual biped robot that generates pacing signals using nonlinear oscillators. This system synchronizes the gait cycles of a human and the robot in a cross-feedback manner, by presenting auditory stimuli that indicate the timing of the partner's foot contacting the ground. Here, we evaluated the effectiveness of this mutual synchrony model in gait stabilization of two Parkinson's disease patients, who display disturbances in rhythm formation and gait festination (accelerating steps). The results showed that the gait festination, as measured as stride time reduction rate, stabilized and accelerated less compared to unassisted walking (i.e., not exposed to the auditory stimuli). In addition, carry-over effects were observed. After termination of the auditory stimuli, the gait remained stabilized. This is the first study using mutual entrainment in dynamically stabilizing gait festination. These results seem to warrant future clinical application of this interpersonal synchrony emulation system for patients with a variety of motor disorders.

DOI： 10.1109/iccme.2011.5876814

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)  

Parkinson’s disease (PD) and basal ganglia dysfunction impairmovement timing, which leads to gait instability and falls. Parkinsonian gait consists of random, disconnected stride times—rather than the 1/f structure observed in healthy gait—and this low fractal scaling of stride times is a strong predictor of falling. Walking with fixed-tempo Rhythmic Auditory Stimulation (RAS) improves many aspects of gait timing; however it requires attention and lowers fractal scaling away from healthy 1/f structure. In this experiment, PD patients and healthy participants walked with a) no auditory stimulation; b) fixed-tempo RAS; and c) an interactiverhythmic auditory stimulation system that used foot sensors and nonlinear oscillators to track and interact with the human’s timing. Patients effortlessly synchronized with the interactive system, their gait felt more stable, and their fractal scaling returned to levels of healthy participants. With the fixed-tempo RAS, patients and healthy participants rarely synchronized, and when they did their fractal scaling declined away from healthy 1/f levels. After removing the interactive rhythmic stimulation, the PD patients’ boost in fractal scaling persisted, indicating that the interaction stabilized the internal rhythm generating system and reintegrated timing networks. Interactive rhythmic auditory stimulation offers a flexible, portable, low-cost, non-invasive rehabilitation system that can improve the mobility, safety, and quality of life of Parkinson’s Disease patients.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The purpose of this study is to support communication of individuals with motor paralysis having difficulty verbally communicating due to illnesses such as Guillain-Barre Syndrome or brain-stem infarction. We have developed and describe a pointing device controlled by DC-coupled electrooculograms (EOGs). The visual angle of the subject is estimated from the amplitude of vertical and horizontal EOGs for determining the two-dimensional pointing position on a PC screen in real time. The eye blinking artifact is reduced using a median filter. Electrode displacement is corrected by considering the potential gradient. Moreover, the position error caused by drift phenomenon is adjusted using head movement based on the vestibule-ocular reflex. The accuracy and operating speed of the proposed method were evaluated among a group of human subjects.

DOI： 10.1109/iembs.2009.5334617

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：第19回創発システムシンポジウム  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：日本神経学会  

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Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：日本神経学会  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution)   Publisher：三共技術総合研究所  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Lecture material (seminar, tutorial, course, lecture, etc.)  

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Language：English   Publishing type：Research paper, summary (international conference)  

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Language：English   Publishing type：Research paper, summary (international conference)  

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Authorship：Lead author  

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Authorship：Lead author  

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Authorship：Lead author   Language：Japanese  

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Authorship：Lead author,　Corresponding author   Language：English  

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Language：English  

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Language：English  

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Authorship：Lead author  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Event date： 2011.5

Language：English  

Considerable research attention has been devoted to interpersonal synchrony and to locomotor control. However their intersection, the interpersonal synchronization of stepping rhythms which is widely observed in our daily life, remains relatively unexplored, despite being a common phenomenon that has considerable rehabilitation potential. Therefore, from the perspective of mutual entrainment of gait rhythms, we have constructed an interpersonal synchrony emulation system between a human subject and a virtual biped robot that generates pacing signals using nonlinear oscillators. This system synchronizes the gait cycles of a human and the robot in a cross-feedback manner, by presenting auditory stimuli that indicate the timing of the partner's foot contacting the ground. Here, we evaluated the effectiveness of this mutual synchrony model in gait stabilization of two Parkinson's disease patients, who display disturbances in rhythm formation and gait festination (accelerating steps). The results showed that the gait festination, as measured as stride time reduction rate, stabilized and accelerated less compared to unassisted walking (i.e., not exposed to the auditory stimuli). In addition, carry-over effects were observed. After termination of the auditory stimuli, the gait remained stabilized. This is the first study using mutual entrainment in dynamically stabilizing gait festination. These results seem to warrant future clinical application of this interpersonal synchrony emulation system for patients with a variety of motor disorders.

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