2021:Journal of Medical Imaging and Health Informatics

Brain Patterns During Single-and Dual-Task Leg Movements

Penghai Li, Han Xu, Abdelkader Nasreddine Belkacem, Jianfeng Zhang, Rui Xu, Xinpu Guo, Xiaotian Wang, Dongyue Wu, Wenjun Tan, Duk Shin, Jun Liang, Chao Chen


The brain is able to engage in dual tasks such as motor imagery (MI) and action observation (AO) or motor execution (ME) with action observation. In this study, we have quantitatively compared event-related desynchronization (ERD) patterns during tasks of pure MI, MI with AO (O-MI), ME, and ME with AO (O-ME) of the leg to investigate the underlying neuronal mechanisms using EEG. Subjects were instructed to imagine or perform rhythmical actions while watching a video of leg movements during O-MI and O-ME tasks; In contrast, subjects imagined and performed the leg movements without observing any video during pure MI and ME tasks. We noticed that the amplitude of ERDs from MI, O-MI, ME and O-ME sequentially increases in central regions of the brain. These quantified ERD patterns in EEG were used to study the differences of brain oscillatory changes among the four tasks. We found that ERDs in motor area were more distinct in O-MI, compared with pure MI. These results suggest that O-MI produced stronger motor activations than MI. Plus, O-ME showed significantly greater activations than ME in the beta band. O-ME has produced stronger neurophysiological effects than MI, and stronger behavioral effects than ME. These empirical results do provide convincing evidence of the dual tasks such combined MI or ME with action observation on brain pattern changes. The video of the goal-directed leg movements is most likely able to improve the ability of performing or imagining movements. O-MI and O-ME may get better and closer therapeutic effects in leg rehabilitation and motor skill training. Furthermore, the extent analysis of ERD may provide the basis for evaluating the ability of O-MI and O-ME in leg rehabilitation and motor skill training.

2021: Advanced Robotics Journal

H Kambara, H Ogawa, A Takagi, D Shin, N Yoshimura, Y Koike: Modulation of wrist stiffness caused by adaptation to stochastic environment

We can catch all sorts of falling objects like eggs or balls. We must predict the dynamical properties of objects to interact with them, but doing so precisely is difficult. The CNS is suggested to modulate the mechanical impedance of the musculoskeletal dynamics to accomplish robust control and overcome variability in environmental dynamics. In this study, we tested the hypothesis that musculoskeletal stiffness increases as the degree of variability in the environment increase through the motor adaptation process. We conducted a ball-catching task experiment in a virtual reality system where the load force of the ball changed every trial and measured the muscle activity in the wrist to estimate its joint stiffness. We found that group level wrist stiffness after adaptation monotonically increased against load force variability. Meanwhile, some participants showed a non-monotonic relationship between wrist stiffness and load force variability. The results of the experiment and computational simulations suggest that the CNS may adapt to a stochastic environment by modulating musculoskeletal stiffness level under the trade-off between movement accuracy and energetic cost.



植松君は不二越の研修が終わり油圧ロボット部署に配属予定で、最近TOEIC 990点満点になり賞金5万円を自慢した(笑)。大塚君は秦野市に家を建てる中。可愛い娘の写真を見せてくれました(笑)。来てくれてありがとう。