Cerebral activation patterns of bimanual and unilateral-limb trainings —Additional verification of an upper-limb rehabilitation robot by using near-infrared spectroscopic technology

Our previous work has introduced a new self-controlled bimanual training robot, and confirmed a positive training effect with increased brain activation amount and motion tracking precision. Even though it was confirmed that the proposed bimanual training induced greater brain activation than single-limb training, we could not assure that bimanual training induced greater cerebral activation only in the dominant hemisphere or in the both hemispheres. Therefore, we performed a new training experiment by quantifying brain activation using near-infrared spectroscopy (NIRS). Bimanual and unilateral-limb tasks were performed in two reverse control directions and in both the active-resisted and active-assisted modes. The inter-hemispheric asymmetry of cerebral activation was compared between the two control directions for different training patterns. As for the comparison of the inter-hemispheric asymmetry of cerebral activation between the two control directions, the unilateral-limb training achieved a greater difference than the bimanual training. The results revealed the bimanual task induced a better symmetry of the two hemispheres in cerebral activation. Therefore, the bimanual training supported by our robot may be more favorable for promoting the recovery and enhancement of two limbs coordination function.