The purpose of this research project is to investigate with the functional magnetic resonance technique, the effects on cortical activity of prolonged immobilization or a reduced use of the upper or lower limbs resulting from orthopaedic surgery (rheumatoid arthroplasty and knee arthroplasty). In addition, we are currently evaluating the behavioural and neurophysiological impact of a mental training based on motor imagination tasks in immobilized patients. This research topic is the result of the collaboration with the Orthopaedic Rehabilitation Unit (Dr Catia Pelosi) and the Orthopaedic Surgery Units (Prof. Valerio Sansone, Dr Maurilio Bruno and Dr Nicola Ursino).