The vibration-induced kinesthetic illusion enhanced by functional electrical stimulation for neurorehabilitation

The final goal of this study is to propose a method to increase the sensory feedbacks for the neurorehabilitation of post-stroke patients. As the rehabilitation method for the post-stroke patients, the neurorehabilitation has been studied to reconstruct the neural network. However, in a post-stroke patient, since sensory feedbacks are weakened, the effect of the neurorehabilitation may be reduced. To increase the sensory feedbacks, some studies have tried to use the kinesthetic illusion induced by vibration stimulation on a human body. On the other hand, it is also known that there is a dead time (latency) to generate the kinesthetic illusion. Furthermore, there is an individual variation of the amount of illusion. To use the kinesthetic illusion in the neurorehabilitation, it is necessary to propose a method to shorten the dead time and increase the amount of illusion. In this study, we propose a method to increase the amount of illusion and reduce the dead time by applying electrical stimulation to human muscles in addition to vibration stimulation. To verify the effectiveness of the proposed method, two experiments were carried out. One is the experiment using vibration stimulation only to create the wrist kinesthetic illusion, and the other is using a combination of vibration stimulation and the Functional Electrical Stimulation (FES) to create the illusion. The experimental results showed that the dead time was reduced by 16% and the angular velocity of the illusion (i.e. the amount of illusion) was increased by 250% compared with the only-vibration stimulation condition. These results suggest that the proposed method is useful as a method to increase sensory feedbacks in neurorehabilitation.