Kenji Kato

Gait disturbance in individuals with spinal cord injury (SCI) at levels rostral to the lumbar locomotor centre results from disconnection between the supraspinal system and the spinal locomotor centre. Here, we present a non-invasive volition-controlled spinal stimulation paradigm that empowers paraplegic individuals to regain stepping control in their impaired legs. Using hand muscle-controlled magnetic stimulation targeting the lumbar spinal motor circuits in the preserved lumber cord, individuals with chronic SCI achieved control of start-stop motion, step length and cadence of bilateral cyclic stepping in paralysed legs. Stimulus-induced cyclic stepping with leg muscle EMG activity was evoked in all participants with complete or incomplete SCI, regardless of the lesion site between the thoracic and lumbar spinal cord. Combining voluntary gait effort with closed-loop stimulation further enhanced leg movements. Repeated application of this closed-loop stimulation led to progressive improvement in stimulus-induced stepping and muscle responses, particularly in participants with thoracic SCI, and in stimulus-free stepping, particularly in participants with incomplete SCI. Our findings indicate that the preserved lumbar spinal motor circuit plays a crucial role in improving stimulus-induced stepping, whereas the preserved descending pathway is required for improving stimulus-free stepping. This non-invasive closed-loop spinal stimulation paradigm bypasses the lesion site on the spinal cord and strengthens both the preserved spinal circuits and the descending pathways to allow bilateral stepping control to be regained after SCI. This approach holds great promise for SCI-related gait rehabilitation because it has the potential to lead to functional recovery. Furthermore, this approach offers a viable alternative for individuals with contraindications to invasive procedures or those who do not consent to surgical treatments.

This study aims to verify the feasibility of measuring the living space of elderly people living alone. The system uses a low risk of identifying personal information by using motion sensors indoors and a smartwatch's GPS (Global Positioning System) records when going out. On the first day of the demonstration, the motion detection sensor system was installed in the home, and the subjects were instructed on using and charging the smartwatch. The participants continued their daily lives for 8 weeks. The indoor system recorded activities such as moving between rooms, using the toilet, and sleeping, while the smartwatch tracked outdoor living spaces using GPS. In the future, we are investigating about how the living space of elderly people living alone is related to their medical characteristics, cognitive function, and physical function, and how it affects their activities of daily living by using our system.Clinical Relevance- The system is expected to enable the monitoring of indoor and outdoor activities of daily living for community-dwelling older adults living alone, and to assess real life-space environments from the perspective of Preventing leakage of personal information and enhancing participant adherence by using human-detection techniques that place minimal burden on older adults.

In this study, we assessed the physical burden on professional caregivers when using a transfer support robot, "Hug," to transfer and move a care recipient. We compared heart rate (HR), heart rate variability (HRV), and the time-series synchronization between HRV and respiration in caregivers using the robot or a normal wheelchair as control. Under both conditions, a commercial wearable device was used to simultaneously obtain electrocardiogram and respiration signals while performing care tasks, which comprised transfer from a bed to a wheelchair or to the robot, movement to a remote location, and transfer to a chair. We found that HR was significantly higher and HRV and wavelet coherence were significantly lower in the control than with Hug during at least the first 30 seconds of rest after the task (p < 0.05). This suggests that Hug could reduce the increase in HR and thereby maintain a more constant rhythm between HRV and respiration during care tasks. A post-task questionnaire also revealed that caregivers felt the physical burden of the tasks was reduced using Hug. Our results suggest that the introduction of transfer support robots can reduce the physical burden for caregivers of daily transfer assistance tasks.

The use of robotic nursing care equipment is an important option for solving the shortage of nursing care personnel, but the effects of its introduction have not been fully quantified. Hence, we aimed to verify that face-to-face care is still provided by caregivers in transfer situations when using robotic nursing care equipment. This study was conducted at a nursing home where the bed-release assist robot "Resyone Plus" is installed on a long-term basis. Caregiver gaze was analyzed quantitatively for one user of the equipment during transfer situations, and communication time, which involved looking at the face of the care recipient, as well as face-to-face vocalization, was measured. The caregiver spent 7.9 times longer looking at the face of and talking to the care recipient when using Resyone than when performing a manual transfer. In addition, the recipient was observed to smile during Resyone separation, which takes about 30 s. The results indicate a possible improvement in the QOL of care recipients through the use of robotic nursing care equipment as a personal care intervention. The ongoing development of robot technology is thus expected to continue to reduce the burden of caregiving as well as to improve the QOL of care recipients.

Many haptic guidance systems have been studied over the years; however, most of them have been limited to predefined guidance methods. Calculating guidance according to the operator's motion is important for efficient human motor adaptation and learning. In this study, we developed a system that haptically provides guidance trajectory by sequential weighting between the operator's trajectory and the ideal trajectory calculated from a predictive-vision system. We investigated whether motion completion with a predictive-vision system affects human motor accuracy and adaptation in time-constrained goal-directed reaching and ball-hitting tasks through subject experiments. The experiment was conducted with 12 healthy participants, and all participants performed ball-hitting tasks. Half of the participants get forceful guidance from the proposed system in the middle of the experiment. We found that the use of the proposed system improved the operator's motor performance. Furthermore, we observed a trend in which the improvement in motor performance using this system correlated with that after the washout of this system. These results suggest that the predictive-vision system effectively enhances motor accuracy to the target error in dynamic and time-constrained reaching and hitting tasks and may contribute to facilitating motor learning.

Assistive robots and technologies can play a key role in supporting the independence and social participation of older people, helping them living healthy lives and reducing the burden on caregivers. To support the effective development of assistive robots and technologies, it is important to develop a “living laboratory” to verify and adapt technology in real-life living spaces. The purpose of this study is to validate assistive robots using a living laboratory that simulates typical indoor and outdoor real-life situations. The rationale is to enable evaluation of daily living activities of older people in a simulated living space. To minimize the risk of trauma after falls, a ceiling suspension system was installed in the living laboratory. Six different commercially available mobility and transfer support robots were introduced and tested. We demonstrated that effective scenarios could be implemented using these assistive robots within the living laboratory. We implemented a 3D markerless motion capturing system in the outdoor space and showed that outdoor activities, including walking up and down a ramp, could be verified with sufficient accuracy in three cases: (i) normal use without a robot, (ii) use of the ceiling suspension system, and (iii) use of a mobility support robot on three healthy subjects. These results suggest that the proposed living laboratory can support testing and verification of assistive robots in simulated living environments.

INTRODUCTION: Emotional contagion is achieved by inferring and emotionally resonating with other persons' feelings. It is unclear whether age-related changes in emotional contagion for infant sounds are modulated by the experience of childbirth or childcare. This study aims to evaluate changes in inference and emotional resonance for positive and negative infant sounds (laughter and crying) among women, based on age and parous experience. METHODS: A total of 241 women (60 young nulliparous, 60 young parous, 60 old nulliparous, and 61 old parous) completed a web-based questionnaire. After listening to three types of infant sounds (laughter, cooing, and crying), participants responded with their valence for hearing infant sounds and estimated infant valence on an 11-point Likert scale. RESULTS: The analysis for emotional resonance revealed that the correlation coefficient between self and estimated infant valences was greater in young parous and old nulliparous women than in young nulliparous women, in laughter and cooing sounds. However, correlation coefficients for crying did not differ among any of the four groups. CONCLUSION: The degree of emotional resonance for infant valence increased depending on age and parous-experience for positive infant sounds.

BACKGROUND: The introduction of nursing care-support devices using robotic technology is expected to reduce the task burden in long-term care facilities. OBJECTIVE: To investigate the use of the rise-assisting robot, Resyone, in extending and improving the life space of nursing home residents with severe care needs. METHODS: We performed a feasibility study in which Resyone was used to facilitate visits to additional sites in and around the nursing home as part of the care package of three residents. Two weeks before and four weeks after implementation of the new arrangements, the 30 caregivers involved were asked to record transfer times and destinations, while also checking the residents' facial expressions. RESULTS: Before implementation, participants had limited life spaces, but afterwards they regularly visited additional destinations including the garden, home entrance and corridors, which previously they had not visited frequently. The residents' facial expressions became more positive and less negative. This study demonstrates that Resyone can enrich care activities in severely disabled individuals. CONCLUSION: These findings suggest that the sustainable use of Resyone would improve the quality of care at care facilities. Moreover, the extension of otherwise limited life space has the potential to improve care receivers' quality of life. TRIAL REGISTRATION: UMIN Clinical Trials Registry No. UMIN000039204 (20/01/2020); retrospectively registered; interventional study; parallel, non-randomized, single blinded. URL of trial registry records: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000044709 .

The long-term use of transfer support robots in nursing facilities is an important option for improving the efficiency of care work. The "Resyone" transfer support robot is a combination of an electric care bed and a wheelchair, and the wheelchair half of the bed can be detached at the touch of a button. The purpose of this study was to investigate how the long-term use of Resyone would improve the performance of transfer assists, such as reducing the need for multiple caregivers. One Resyone was installed in a nursing facility in Japan and 17 caregivers used it for more than 11 months. The time and number of caregivers required for each transfer assist were surveyed for three 1-week periods: 1 week before (Phase 1) and at 3 weeks (Phase 2) and 11 months (Phase 3) after the introduction of Resyone. In Phase 1, approximately 60% of all transfer assists were performed by two caregivers, but in Phase 2, this was reduced to approximately 20%, and finally, in Phase 3, all transfer assists were performed by a single caregiver. These results suggested that the long-term use of Resyone was associated with improved work efficiency in transfer assistance in a nursing facility.

OBJECTIVE: The aim of this study was to assess safety issues of self-controlled repetitive trans-vertebral magnetic stimulation (rTVMS) in humans. METHODS: We investigated effects of self-controlled rTVMS (≤20 Hz, ≤90% intensity) on vital signs and subjective sensations in 1690 trials of 30 healthy volunteers and 12 patients with spinal cord disorders. RESULTS: Healthy volunteers and the patients received 4595 ± 2345, and 4450 ± 2304 pulses in one day, respectively. No serious adverse events were observed in any participants, and only minor events were seen as follows. While blood pressure was unaffected in the patients, the diastolic blood pressure increased slightly after rTVMS in healthy volunteers. The peripheral capillary oxygen saturation increased after rTVMS in healthy volunteers. "Pain" or "Discomfort" was reported in approximately 10% of trials in both participants groups. Degree of the evoked sensation positively correlated with stimulus intensity and was affected by the site of stimulation. CONCLUSION: Self-controlled rTVMS (≤20 Hz and ≤90% intensity) did not induce any serious adverse effects in healthy volunteers and patients with spinal cord disorders. SIGNIFICANCE: Our results indicate that rTVMS can be used safely in physiological investigations in healthy volunteers and also as treatment for neurological disorders.

BACKGROUND: To reduce the physical burden of caregivers, wearable transfer support robots are highly desirable. Although these robots are reportedly effective for specific tasks in experimental environments, there is little information about their effectiveness at nursing care facilities. The aim of this study was to identify care tasks and operations suitable for the use of these robots among caregivers in nursing facilities where these robots have been in use on a daily basis. METHODS: A 1-min observational time-motion analysis was conducted to examine care tasks and operations in two nursing facilities where wearable transfer support robots, namely Muscle Suit or HAL® Lumbar Type for Care Support, have been used routinely on a daily basis for more than 24 months. RESULTS: Analysis of the care tasks and their time ratio while wearing the equipment revealed that both robots were used conspicuously for direct care in over 70% of transits, especially during transfer assistance and toileting care. Furthermore, these robots were used intensively in the morning along with wake-up calls to care recipients, where pre-assigned wearers used them as part of their "routine work." CONCLUSIONS: We found that these wearable transfer support robots enabled effective performance of care tasks and operations in nursing facilities where these robots have been used on a daily basis for an extended period of time. These results may lead to the effective implementation and sustained operation of other types of care robots in the future. TRIAL REGISTRATION: UMIN Clinical Trials Registry no. UMIN000039204 . Trial registration date: January 21, 2020. Interventional study. Parallel, non-randomized, single blinded.

BACKGROUND: Oscillations in the resting-state scalp electroencephalogram (EEG) represent various intrinsic brain activities. One of the characteristic EEG oscillations is the sensorimotor rhythm (SMR)-with its arch-shaped waveform in alpha- and betabands-that reflect sensorimotor activity. The representation of sensorimotor activity by the SMR depends on the signal-to-noise ratio achieved by EEG spatial filters. NEW METHOD: We employed simultaneous recording of EEG and functional magnetic resonance imaging, and 10-min resting-state brain activities were recorded in 19 healthy volunteers. To compare the EEG spatial-filtering methods commonly used for extracting sensorimotor cortical activities, we assessed nine different spatial-filters: a default reference of EEG amplifier system, a common average reference (CAR), small-, middle- and large-Laplacian filters, and four types of bipolar manners (C3-Cz, C3-F3, C3-P3, and C3-T7). We identified the brain region that correlated with the EEG-SMR power obtained after each spatial-filtering method was applied. Subsequently, we calculated the proportion of the significant voxels in the sensorimotor cortex as well as the sensorimotor occupancy in all significant regions to examine the sensitivity and specificity of each spatial-filter. RESULTS: The CAR and large-Laplacian spatial-filters were superior at improving the signal-to-noise ratios for extracting sensorimotor activity from the EEG-SMR signal. COMPARISON WITH EXISTING METHODS: Our results are consistent with the spatial-filter selection to extract task-dependent activation for better control of EEG-SMR-based interventions. Our approach has the potential to identify the optimal spatial-filter for EEG-SMR. CONCLUSIONS: Evaluating spatial-filters for extracting spontaneous sensorimotor activity from the EEG is a useful procedure for constructing more effective EEG-SMR-based interventions.

OBJECTIVE: Spinal stimulation is a promising method for restoring the function of paralyzed limbs following neurological damage to descending pathways. The present study examined the forelimb movements and muscle responses evoked by subdural spinal stimulation of the cervical cord in sedated monkeys or during an arm-reaching task. APPROACH: We chronically implanted a platinum subdural electrode array with eight channels over the dorsal-lateral aspect of the cervical enlargement. The electrodes had a diameter of 1 mm and an inter-electrode center-to-center distance of 3 mm. Subdural spinal micro-stimulation was delivered at sites while the monkeys were sedated or performed arm-reaching movements. MAIN RESULTS: The evoked movements clearly showed the somatotopic map of the output sites; the electrodes located on the rostral cervical cord tended to induce movements of the proximal arm, whereas the caudal electrodes tended to induce movements of the distal joints, such as the wrist and digits. To document the muscle responses evoked by subdural spinal stimulation, stimulus-triggered averages of rectified electromyograms were compiled when the monkeys performed an arm-reaching task or were sedated. Under sedation, evoked facilitative muscle responses were observed in vicinity muscles. In contrast, during the task, stimulation evoked facilitative or suppressive responses in multiple muscles, including those located on proximal and distal joints, while somatotopy became blurred under sedation. Furthermore, stimulation during tasks activated synergistic muscle groups. For example, stimuli strongly facilitated finger extensor muscles, but suppressed the antagonist muscles. SIGNIFICANCE: These dynamic changes in muscle representation by subdural cervical spinal stimulation between sedated and awake states help our understanding of the nature of spinal circuits and will facilitate the development of neuroprosthetic technology to regain motor function after neural damage to the descending pathways.

Regaining the function of an impaired limb is highly desirable in paralyzed individuals. One possible avenue to achieve this goal is to bridge the interrupted pathway between preserved neural structures and muscles using a brain-computer interface. Here, we demonstrate that monkeys with subcortical stroke were able to learn to use an artificial cortico-muscular connection (ACMC), which transforms cortical activity into electrical stimulation to the hand muscles, to regain volitional control of a paralysed hand. The ACMC induced an adaptive change of cortical activities throughout an extensive cortical area. In a targeted manner, modulating high-gamma activity became localized around an arbitrarily-selected cortical site controlling stimulation to the muscles. This adaptive change could be reset and localized rapidly to a new cortical site. Thus, the ACMC imparts new function for muscle control to connected cortical sites and triggers cortical adaptation to regain impaired motor function after stroke.

Gait disturbance in individuals with spinal cord lesion is attributed to the interruption of descending pathways to the spinal locomotor center, whereas neural circuits below and above the lesion maintain their functional capability. An artificial neural connection (ANC), which bridges supraspinal centers and locomotor networks in the lumbar spinal cord beyond the lesion site, may restore the functional impairment. To achieve an ANC that sends descending voluntary commands to the lumbar locomotor center and bypasses the thoracic spinal cord, upper limb muscle activity was converted to magnetic stimuli delivered noninvasively over the lumbar vertebra. Healthy participants were able to initiate and terminate walking-like behavior and to control the step cycle through an ANC controlled by volitional upper limb muscle activity. The walking-like behavior stopped just after the ANC was disconnected from the participants even when the participant continued to swing arms. Furthermore, additional simultaneous peripheral electrical stimulation to the foot via the ANC enhanced this walking-like behavior. Kinematics of the induced behaviors were identical to those observed in voluntary walking. These results demonstrate that the ANC induces volitionally controlled, walking-like behavior of the legs. This paradigm may be able to compensate for the dysfunction of descending pathways by sending commands to the preserved locomotor center at the lumbar spinal cord and may enable individuals with paraplegia to regain volitionally controlled walking.