Neurorehabilitation Method for Preventing the Collapse of Internal Model: Verification of Unconscious Motor Change Caused by Implicit Error Involved in Multimodal Sensory FBs(Feedbacks)

It remains challenging for patients with stroke to regain the proper gait they had before stroke onset. In this study, one of the significant reasons for the problem is assumed to be the collapse of patients’ internal model. Therefore, this study aimed to propose a method for lower-limb rehabilitation in the acute phase to prevent the collapse of the internal model and simultaneously promote voluntariness.To verify the effect of the proposed method and determine the optimal FB conditions, a supine pseudo-walking system has been developed providing multimodal sensory FBs, including somatosensory FB (walking on the walking robot), load transfer FB (plantar vibration provided by the robot), and visual FB (walking scene shown in virtual reality).First, the implicit error range of each sensory FB that was unable to recognize was investigated according to Weber’s law. Subsequently, 12 participants were asked to perform 12 steps of walking exercise in the system to evaluate the unconscious motor-changing effect due to different/multimodal FBs. Errors were presented at the 7th step in either three FBs in the ratio determined or their combinations (two or three types of FBs simultaneously changing).Second, to examine whether the effect can last and influence the motion after the training, a pre–post comparison test was performed with the training in the middle, wherein implicit errors were presented in the three kinds of FBs.The results show that presenting implicit error can cause motor change, and multiple types of FBs may have a better effect. The statistical data of 12 participants of the pre–post comparison test show that the average integrated electromyogram in the post-test appears significantly larger than that in the pre-test. The result indicates that the motor-changing effect of the proposed method has a subsequent influence on motion and shows the possibility of the future application of the proposed method to the rehabilitation field.