Validation of bimanual-coordinated training supported by a new upper-limb rehabilitation robot: A near-infrared spectroscopy study

Purpose: Our previous work proposed a rehabilitation robot to support bimanual-coordinated training not only in active-assisted and passive-driven modes but also in active-resisted mode. However, assessment of training effect was only focused on the improvements of subjects' motion-tracking precisions. This paper presents an evaluation strategy based on variations in both cerebral activation level (CAL) and motion-tracking precision. Method:Fourteen healthy subjects participated in motion-tracking training in bimanual active-assisted and active-resisted modes, and in single right-limb and left-limb modes, with haemoglobin concentration and motion-tracking errors being measured simultaneously. Analyses of variance (ANOVA) of the CAL and motion-tracking errors were performed to investigate bimanual training effect and the difference between bimanual and single-limb trainings in activating the brain.Results: In the bimanual modes, both the CAL and motion-tracking precision significantly increased after training. And the CAL induced in the bimanual trainings were significantly greater than in the single-limb trainings. Conclusions:Significant enhancement of the CAL and motion-tracking precision confirmed a positive training effect on enhancing the bimanual-coordination capability of healthy subjects. Compared to the single-limb modes, the higher CAL in the bimanual modes demonstrated the potential of the proposed bimanual training for improving the functional integrity of the two hemispheres. Implications for Rehabilitation The designed robot supports bimanual and unilateral-limb training in active-resisted, active-assisted, and passive-driven modes. Thus, it has a great potential for delivering rehabilitation training to patients with different degrees of impairments. The characteristics of self-controlled bimanual training and force sensation capability make the subjects participate the training actively, and enable them to regulate the forces of the two limbs in time. Furthermore, the above characteristics are favorable for inducing functional integrity of the two hemispheres, and thus, make the robot preferable to exercise the movement coordination capability of bilateral arms. In active-resisted mode, the two limbs can exert two forces in a reverse direction. Since many tasks in daily life require the two limbs to give two forces in a reverse direction, this feature is favorable for advancing the process of adapting patients to daily life.