Analysis of upper limb performance of elderly people using a mechatronic system

This work represents the first attempt to investigate the age-related modifications of upper limb motor control strategy implemented by the central nervous system (CNS) by using a mechatronic system. In particular, this system was used with a twofold objective: (1) to verify whether aging provokes a reduction of motor performance; (2) to understand the causes of these modifications. The performance of elderly and young people were compared by using a two degrees of freedom robotic device (i.e., the MIT-MANUS). This particular machine was designed to assist stroke patients during rehabilitation, but its mechanical characteristics, such as a low intrinsic end-point impedance, and a nearly-isotropic inertia, make it a good instrument for the analysis of CNS behaviour because it does not affect the way subjects try to perform the task. Reaching experiments were carried out in a null field, asking the subjects to carry out the task in the most natural way, without giving limitation in time or velocity. The comparison of the results achieved by elderly and young people seems to show that aging does not affect the programming of the internal model, but it involves the feedback sensory motor pathway, which is used to predict the kinematic trajectory of the hand according to both proprioceptive and visual inputs.