||Ruoxi Wang, Qi An, Ningjia Yang, Hiroki Kogami, Kazunori Yoshida, Hiroyuki Hamada, Shingo Shimoda, Hiroshi Yamasaki, Moeka Sonoo, Fady Alnajjar, Noriaki Hattori, Kouji Takahashi, Takanori Fujii, Hironori Otomune, Ichiro Miyai, Atsushi Yamashita and Hajime Asama, Muscle Tension Analysis in Stroke Patient Sit-to-Stand Motion by Joint Torque-Based Normalization, 5th International Conference on NeuroRehabilitation (ICNR2020), 2020.11.
||Ningjia Yang, Qi An, Hiroki Kogami, Hiroshi Yamakawa, Yusuke Tamura, Kouji Takahashi, Makoto Kinomoto, Hiroshi Yamasaki, Matti Itkonen, Fady Shibata-Alnajjar, Shingo Shimoda, Noriaki Hattori, Takanori Fujii, Hironori Otomune, Ichiro Miyai, Atsushi Yamashita, Hajime Asama, Temporal Features of Muscle Synergies in Sit-to-Stand Motion Reflect the Motor Impairment of Post-Stroke Patients, IEEE Transactions on Neural Systems and Rehabilitation Engineering, 10.1109/TNSRE.2019.2939193, 27, 10, 2118-2127, 2019.10, Sit-to-stand (STS) motion is an important daily activity, and many post-stroke patients have difficulty performing STS motion. Previous studies found that there are four muscle synergies (synchronized muscle activations) in the STS motion of healthy adults. However, for post-stroke patients, it is unclear whether muscle synergies change and which features primarily reflect motor impairment. Here, we use a machine learning method to demonstrate that temporal features in two muscle synergies that contribute to hip rising and balance maintenance motion reflect the motor impairment of post-stroke patients. Analyzing the muscle synergies of age-matched healthy elderly people ( $n = 12$ ) and post-stroke patients ( $n = 33$ ), we found that the same four muscle synergies could account for the muscle activity of post-stroke patients. Also, we were able to distinguish post-stroke patients from healthy people on the basis of the temporal features of these muscle synergies. Furthermore, these temporal features were found to correlate with motor impairment of post-stroke patients. We conclude that post-stroke patients can still utilize the same number of muscle synergies as healthy people, but the temporal structure of muscle synergies changes as a result of motor impairment. This could lead to a new rehabilitation strategy for post-stroke patients that focuses on activation timing of muscle synergies..
||Hiroki Kogami, Qi An, Ningjia Yang, Hiroshi Yamakawa, Yusuke Tamura, Atsushi Yamashita, Hajime Asama, Shingo Shimoda, Hiroshi Yamasaki, Matti Itkonen, Fady Shibata-Alnajjar, Noriaki Hattori, Makoto Kinomoto, Kouji Takahashi, Takanori Fujii, Hironori Otomune, Ichiro Miyai, Effect of Physical Therapy on Muscle Synergy Structure during Standing-Up Motion of Hemiplegic Patients, IEEE Robotics and Automation Letters, 10.1109/LRA.2018.2811050, 3, 3, 2229-2236, 2018.07, Stroke patients suffer from declined physical ability, and it is important to analyze rehabilitation intervention and clarify its effect on the motion of patients. In this study, the effect of intervention on the standing-up motion of stroke patients is investigated. First, the intervention timing of a physical therapist (PT) is analyzed quantitatively from the muscle activity of upper limbs during therapy. Next, the intervention effect is evaluated based on body kinematics and muscle synergy. In this study, twenty trials are conducted, in which the standing-up motion of hemiplegic patients (n=12) is measured with and without the intervention by a PT. The results show that PTs teach hemiplegic patients the timing of lifting their buttocks during standing-up motion. Furthermore, it has been found that this intervention could improve the standing-up motion, although stroke patients had inadequate muscle synergy structure. In particular, some patients had delayed activation of the synergy and they could only stood up after they moved their center of mass toward their feet. However, the intervention by PTs could induce earlier activation of the synergy. Moreover, the intervention could properly shorten the activation duration of muscle synergy for those who had unusually inappropriate longer activation of synergy. These results imply that disordered and inadequate muscle synergy structure can be improved by proper intervention, and this study contributes to the further development of new rehabilitation methodologies..
||Cara E. Stepp, Qi An, Yoky Matsuoka, Repeated training with augmentative vibrotactile feedback increases object manipulation performance, PloS one, 10.1371/journal.pone.0032743, 7, 2, 2012.02, Most users of prosthetic hands must rely on visual feedback alone, which requires visual attention and cognitive resources. Providing haptic feedback of variables relevant to manipulation, such as contact force, may thus improve the usability of prosthetic hands for tasks of daily living. Vibrotactile stimulation was explored as a feedback modality in ten unimpaired participants across eight sessions in a two-week period. Participants used their right index finger to perform a virtual object manipulation task with both visual and augmentative vibrotactile feedback related to force. Through repeated training, participants were able to learn to use the vibrotactile feedback to significantly improve object manipulation. Removal of vibrotactile feedback in session 8 significantly reduced task performance. These results suggest that vibrotactile feedback paired with training may enhance the manipulation ability of prosthetic hand users without the need for more invasive strategies..