Neurophysiological mechanisms underlying action observation treatment for upper limb stroke rehabilitation: A mini-review

Action Observation Treatment (AOT) has been demonstrated to promote motor recovery in stroke survivors. This approach consists in the observation of goal-directed actions, followed by their imitation. AOT exploits the functional properties of the Mirror Neuron System (MNS), which activates motor representations during the observation of others' actions, thereby triggering a process known as "motor resonance". This mechanism enhances corticospinal excitability, supporting neural plasticity. During AOT, the MNS becomes finely tuned, promoting neuroplastic changes crucial for motor recovery. However, the cortico-cerebellar and subcortical mechanisms underlying the effectiveness of this treatment are unclear. In this review, we describe first the theoretical background of AOT, discussing the key concepts of motor resonance and imitation-based learning. Second, we focus on the cortico-cerebellar and subcortical circuits crucial in the modulation of MNS activity during imitation. Third, we summarize current evidence regarding the neural circuits potentially involved in post-AOT recovery in stroke patients. In the final part, we outline future research directions, proposing personalized interventions based on Virtual Reality and Neurofeedback to maximize treatment efficacy.