Reaching tasks in an altered dynamic environment: Motor adaptation in FRDA patients

Abstract

Introduction: In the last few years, robotic devices are extensively employed to exploit how the Central Nervous System (CNS) learns to control movements in different dynamical conditions. It was demonstrate that normally developed subjects can adapt to novel dynamic environments, tuning an internal model of the armenvironment to compensate systematically applied forces, and showing an after-effect that appears when the force field is unexpectedly removed [1]. Itwasalso found that this capability is at least partially still present in subjects affected by Huntington’s disease, or in stroke survivor, but not in subjectswith cerebellar atrophy [2]. The aims of this work were (1) to assess the upper limb function in subjects affected by Friedreich’s ataxia (FRDA), and (2) to verify the capability of FRDA patients to adapt to a velocity dependent force field. Methods: Ten FRDA patients (7–53 years) and nine healthy controls (22–29 years) were involved in the study. Subjects were instructed to perform reaching planar movements by means of a robotic device (InMotionArm Robot, IMT, USA) that provided kinematic data of the end-effector with two absolute encoders. The protocol included 48 point-to-point movements, repeated three times with the following conditions: (1) no field (Familiarization