Home-based Action Observation Treatment With Virtual-reality for Arm Rehabilitation in People With Multiple Sclerosis

Action Observation Treatment (AOT) is a rehabilitative strategy which has been proposed as a promising approach to improve motor performance in neurological conditions, including multiple sclerosis (MS). In this clinical trial, the investigators aim to explore the role of a home-based AOT with virtual reality (VR) in improving upper limb motor function in people with MS (PwMS). The objectives are: * To compare the effects of home-based VR-AOT versus VR-landscape observation (LO) on upper limb motor performance; * To measure brain network functional changes (functional plasticity) and structural variations of gray matter (GM) and white matter (WM) (structural plasticity) using advanced magnetic resonance imaging (MRI) techniques following VR-AOT and VR-LO; * To study the correlations between MRI changes and clinical improvements and the predictors of VR-AOT efficacy. All participants will undergo treatment sessions for 3 weeks (5 consecutive days/week, total=15 sessions lasting 30 minutes each). Those in the VR-AOT group will observe, imagine and execute two upper limb motor tasks in each session. Those in the VR-LO group will perform the same tasks, but they will observe inanimate landscapes beforehand instead.