Age-related Declines in Sensorimotor Proficiency are Specific to the Tested Motor Skill Component.

This study utilized a 3-degree of freedom robotic device (Wristbot) to examine wrist proprioception and eye-hand coordination in a cross-sectional sample of sixty-three young adults (19-29 years), 20 older young adults (30-49), and 17 older adults (50 years and older). Results indicated differences in the emergence of age-related declines in sensorimotor functioning depending on the tested motor skill component. While young adults exhibited smaller matching error and lower variability compared to older young adults and older adults on the proprioception task, we observed lower times-on-target and higher Linearity indices for participants older than 50 years of age compared to both young adults and older young adults. The present results provide necessary quantitative information on sensorimotor function in adulthood, and have implications for the early diagnosis and effective management of sensorimotor dysfunction in clinical settings using a commercially available robotic device.

Work with me, not for me: Relationship between robotic assistance and performance in subacute and chronic stroke patients.

INTRODUCTION: Studies in robotic therapy which applied the performance enhancement approach report improvements in motor performance during training, though these improvements do not always transfer to motor learning. OBJECTIVES: We postulate that there exists an assistance threshold for which performance saturates. Above this threshold, the robot's input outweighs the patient's input and likely learning is not fostered. This study investigated the relationship between assistance and performance changes in stroke patients to find the assistance threshold for performance saturation. METHODS: Twelve subacute and chronic stroke patients engaged in five sessions (over two weeks, each 60 min) in which they performed a reaching task with the rehabilitation robot H-Man in presence of varying levels of haptic assistance (50 N/m to 290 N/m, randomized order). In two additional sessions, a therapist manually tuned the assistance to promote maximal motor learning. RESULTS: Higher levels of assistance resulted in smoother and faster performance that saturated at assistance levels with K ≥ 110 N/m. Also, the therapist selected assistance levels of K = 175 N/m or below. CONCLUSION: The findings of the study indicate that low levels of assistance (K ≤ 175 N/m) can sufficiently induce a significant change in performance.