The driving idea of this project is to use new imaging techniques during 0functional movements to study relearning during a typical rehabilitation session. The novelty of this project is to move from studies inquiring changes in brain activity patterns before and after rehabilitation toward a paradigm in which cortical activity is studied during the execution of the exercise. This would allow better understanding of cortical mechanisms underpinning functional improvements. The project builds on preceding studies, partially funded by FISM, from the three research units involved in this project, aimed at assessing the impact of rehabilitation on mobility and balance and at assessing the effects of neurorehabilitation on brain plasticity. In this study, we will include 40 healthy subjects and a sample of 20 consecutive People with Multiple Sclerosis (PwMS), and we will investigate brain cortical activity during a typical session of task-oriented exercises. In specific, participants will undergo a treadmill training in which they will be required to keep their trunk and head stable in space using a biofeedback device. To study the effects of the session in improving dynamic stability, Head/trunk movements will be registered by inertial measurement units, while cortical activity will be concurrently assessed by functional near-infrared spectroscopy (fNIRS). The first phase of the project will include healthy subjects and will be useful to understand the main cortical areas involved in the proposed motor tasks, in order to design the appropriate montage and protocol for fNIRS acquisition in PwMS. Finally, the analysis of the possible differences in cortical activation during different experimental conditions (e.g., biofeedback rehabilitation) in healthy subjects and PwMS will serve to develop a model for neurological rehabilitation.