Research Institute of National Rehabilitation Center for Persons with Disabilities

Tokorozawa, Japan

Research Institute of National Rehabilitation Center for Persons with Disabilities

Tokorozawa, Japan
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Wada M.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Ide M.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Ide M.,Japan Society for the Promotion of Science
Experimental Brain Research | Year: 2016

Persons with high autistic traits showed diverse reactions as to their multisensory integration, whereas neurotypical persons adequately integrate visual and tactile information. Successive visual stimuli sometimes interfere ordering of successive tactile stimuli. Presentation of a hand-shaped object would affect the interference. Besides, its associations with autistic traits have not been reported. Here, we investigated the effect of a rubber hand presentation on interferences to tactile temporal order judgment by successive visual stimuli. We also investigated whether individual differences associated with autistic traits. A rubber hand was placed palm down in front of the participant in one condition, while in other conditions, it was inverted or was not presented. Participants were required to judge the temporal order of tactile stimuli presented to the index finger and ring finger of their unseen right hand, and needed to ignore the visual stimuli placed on the corresponding fingers of the rubber hand. When incongruent visual stimuli were delivered along with presentation of the rubber hand, the participant’s judgment was notably reversed. In contrast, the degree of reversals significantly decreased when the rubber hand was not presented or presented in an inverted direction. Additionally, we found that participants with high autistic traits tended to show large reversal with the rubber hand presentation, while they showed small reversal when the rubber hand was inverted. Our results suggest that rubber hand corresponding to one’s own hand facilitates visuotactile interference. Furthermore, autistic traits may affect the integration of visuotactile inputs when the rubber hand is presented. © 2015, Springer-Verlag Berlin Heidelberg.


Ide M.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Ide M.,Japan Society for the Promotion of Science | Wada M.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Frontiers in Integrative Neuroscience | Year: 2016

In a rubber hand illusion (RHI) task, synchronous brush stroking of a rubber hand and a participant's hidden hand induces body ownership of the rubber hand. The effects of spatial distances and temporal lags on the RHI have been extensively examined; however, the effect of periodicity of the stimuli on illusory body ownership has not been examined. Meanwhile, the occurrence of RHI tends to be weak in individuals with autism-spectrum disorders (ASD) and high autistic traits. Preference for stimulus having regularity of tempo is generally observed in individuals with ASD, and thus, periodic stimulation might be more effective to elicit the body ownership illusion in individuals with high autistic traits. Hence, we investigated whether stimulus periodicity influenced RHI as well as its association with participant's autistic traits. Brush strokes were applied to a participant's own hand and the rubber hand periodically (2 s) or non-periodically (1-3 s), either synchronously or asynchronously. Two blocks were performed in each condition. We found that periodic stimulation enhanced the spatial updating of tactile sensation induced by RHI in the subsequent block in participants with high autistic traits, whereas both periodic and non-periodic stimulation strongly elicited RHI in blocks 1 and 2. These results indicate that the periodicity of stimulation has different effects based on an individual's autistic traits. Since individuals with ASD are known to sustain their focus on interoceptive sensations (heartbeats), a periodic stimulation that is potentially correlated with heartbeats might be effective to enhance the visuotactile integration during RHI in individuals with high autistic traits. © 2016 Ide and Wada.


Sakurada T.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Kawase T.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Takano K.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Komatsu T.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Kansaku K.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Frontiers in Neuroscience | Year: 2013

A brain-machine interface (BMI) is an interface technology that uses neurophysiological signals from the brain to control external machines. Recent invasive BMI technologies have succeeded in the asynchronous control of robot arms for a useful series of actions, such as reaching and grasping. In this study, we developed non-invasive BMI technologies aiming to make such useful movements using the subject's own hands by preparing a BMI-based occupational therapy assist suit (BOTAS). We prepared a pre-recorded series of useful actions-a grasping-a-ball movement and a carrying-the-ball movement-and added asynchronous control using steady-state visual evoked potential (SSVEP) signals. A SSVEP signal was used to trigger the grasping-a-ball movement and another SSVEP signal was used to trigger the carrying-the-ball movement. A support vector machine was used to classify EEG signals recorded from the visual cortex (Oz) in real time. Untrained, able-bodied participants (n = 12) operated the system successfully. Classification accuracy and time required for SSVEP detection were ~88% and 3 s, respectively. We further recruited three patients with upper cervical spinal cord injuries (SCIs); they also succeeded in operating the system without training. These data suggest that our BOTAS system is potentially useful in terms of rehabilitation of patients with upper limb disabilities. © 2013 Sakurada, Kawase, Takano, Komatsu and Kansaku.


Ueyama Y.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Frontiers in Computational Neuroscience | Year: 2014

We propose a mini-max feedback control (MMFC) model as a robust approach to human motor control under conditions of uncertain dynamics, such as structural uncertainty. The MMFC model is an expansion of the optimal feedback control (OFC) model. According to this scheme, motor commands are generated to minimize the maximal cost, based on an assumption of worst-case uncertainty, characterized by familiarity with novel dynamics. We simulated linear dynamic systems with different types of force fields-stable and unstable dynamics-and compared the performance of MMFC to that of OFC. MMFC delivered better performance than OFC in terms of stability and the achievement of tasks. Moreover, the gain in positional feedback with the MMFC model in the unstable dynamics was tuned to the direction of instability. It is assumed that the shape modulations of the gain in positional feedback in unstable dynamics played the same role as that played by end-point stiffness observed in human studies. Accordingly, we suggest that MMFC is a plausible model that predicts motor behavior under conditions of uncertain dynamics. © 2014 Ueyama.


Kathner I.,University of Würzburg | Kubler A.,University of Würzburg | Halder S.,University of Würzburg | Halder S.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Frontiers in Neuroscience | Year: 2015

Visual ERP (P300) based brain-computer interfaces (BCIs) allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g. at a patient's bedside). To explore if similar accuracies can be achieved with a virtual reality (VR) headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS) to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5x5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A), the same 5x5 matrix filled the field of view of the user. In the second (glasses B), single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on 3 different occasions (glasses A condition only). For healthy participants, average online spelling accuracies were 94% (15.5 bits/min) using three flash sequences for spelling with the monitor and glasses A and 96% (16.2 bits/min) with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100% (10 bits/min) using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100% accuracy). We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely paralyzed persons. © 2015 Käthner, Kübler and Halder.


Takano K.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Hata N.,Research Institute of National Rehabilitation Center for Persons with Disabilities | Kansaku K.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Frontiers in Neuroscience | Year: 2011

The brain-machine interface (BMI) or brain-computer interface is a new interface technology that uses neurophysiological signals from the brain to control external machines or computers. This technology is expected to support daily activities, especially for persons with disabilities. To expand the range of activities enabled by this type of interface, here, we added augmented reality (AR) to a P300-based BMI. In this new system, we used a see-through head-mount display (HMD) to create control panels with flicker visual stimuli to support the user in areas close to controllable devices. When the attached camera detects an AR marker, the position and orientation of the marker are calculated, and the control panel for the pre-assigned appliance is created by the AR system and superimposed on the HMD. The participants were required to control system-compatible devices, and they successfully operated them without significant training. Online performance with the HMD was not different from that using an LCD monitor. Posterior and lateral (right or left) channel selections contributed to operation of the AR-BMI with both the HMD and LCD monitor. Our results indicate that AR-BMI systems operated with a see-through HMD may be useful in building advanced intelligent environments. © 2011 Takano, Hata and Kansaku.


Ueyama Y.,Research Institute of National Rehabilitation Center for Persons with Disabilities
PLoS ONE | Year: 2015

One of the core features of autism spectrum disorder (ASD) is impaired reciprocal social interaction, especially in processing emotional information. Social robots are used to encourage children with ASD to take the initiative and to interact with the robotic tools to stimulate emotional responses. However, the existing evidence is limited by poor trial designs. The purpose of this study was to provide computational evidence in support of robot-Assisted therapy for children with ASD. We thus propose an emotional model of ASD that adapts a Bayesian model of the uncanny valley effect, which holds that a human-looking robot can provoke repulsion and sensations of eeriness. Based on the unique emotional responses of children with ASD to the robots, we postulate that ASD induces a unique emotional response curve, more like a cliff than a valley. Thus, we performed numerical simulations of robot-Assisted therapy to evaluate its effects. The results showed that, although a stimulus fell into the uncanny valley in the typical condition, it was effective at avoiding the uncanny cliff in the ASD condition. Consequently, individuals with ASD may find it more comfortable, and may modify their emotional response, if the robots look like deformed humans, even if they appear "creepy" to typical individuals. Therefore, we suggest that our model explains the effects of robot-Assisted therapy in children with ASD and that humanlooking robots may have potential advantages for improving social interactions in ASD. Copyright: © 2015 Yuki Ueyama.


Ueyama Y.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

We evaluated the efficiency of robotic therapy for stroke survivors by using a computational approach in motor theory with a stroke rehabilitation model. In computational neuroscience, hand movement can be represented by population coding of neuronal preferred directions (PDs) in the motor cortex. We modeled the recovery processes of arm movement in conventional and robotic therapies as reoptimization of PDs in different learning rules, and compared the efficiencies after stroke. Conventional therapy did not induce complete recovery of stroke lesions, and the neuronal state depended on the training direction. However, robotic therapy reoptimized the PDs uniformly regardless of the training direction. These observations suggest that robotic therapy may be effective for recovery and not have a negative effect on motor performance depending the training direction. Furthermore, this study provides computational evidence to promote robotic therapy for stroke rehabilitation. © 2014 Springer International Publishing.


Ueyama Y.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

We propose a computational model for anti-Bayesian sensory integration of human behavioral actions and perception in the size-weight illusion (SWI). The SWI refers to the fact that people judge the smaller of two equally weighted objects to heavier when lifted. Many aspects of human perceptual and motor behavior can be modeled with Bayesian statistics. However, the SWI cannot be explained on the basis of Bayesian integration, and the nervous system is thought to use two entirely different mechanisms to integrate prior expectations with current sensory information about object weight. Our proposed model is defined as a state estimator, combining a Kalman filter and a H∞ filter. As a result, the model not only predicted the anti-Bayesian estimation of the weight but also the Bayesian estimation of the motor behavior. Therefore, we hypothesize that the SWI is realized by a H∞ filter and a Kalman filter. © Springer International Publishing Switzerland 2014.


Ueyama Y.,Research Institute of National Rehabilitation Center for Persons with Disabilities
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Several studies have aimed to provide computational evidence of poststroke interventions because how to optimize motor recovery has been unclear. Although muscle synergies may be the basic control modules on which the central nervous system relies to generate motion, previous computational evidence ignored muscle activity. This study proposes a model of motor impairment after stroke for predicting muscle activity patterns. This model can reproduce a peculiar muscle activation pattern observed in stroke patients. Moreover, we carried out a simulation of the motor recovery process by minimizing the output torque error. As a result, the muscle activation patterns could not be modified to the intact condition, because the recovery process might fall into a local minimum. Thus, we suggest that our model could reproduce muscle activities after stroke, and that muscle synergy cannot be recovered by ‘conventional’ processes of the poststroke rehabilitation. © Springer International Publishing Switzerland 2015.

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