EVALUATION COMMITTEE

The Faculty Council has appointed the following adjudication committee to evaluate the thesis and the associated lecture: 

• Dr. Elia Valentini, Department of Psychology, University of Essex, UK.
• Dr. Elisa Carlino, Department of Neuroscience, University of Turin, Italy.
• Dr. Strahinja Dosen, HST, Aalborg University (Chairman).

Moderator:
Dr. Laura Petrini, HST, Aalborg University.

Abstract

Placing a mirror adequately oriented, the motion of one limb may result in the illusion of the movement of the other limb. This technique is known as Mirror Visual Feedback (MVF) and it has been often used to treat several chronic pain conditions, such as phantom limb pain, complex regional pain syndrome, post-stroke paralysis or stiffness. However, the brain cortical areas and the neurophysiological mechanisms underpinning this illusory phenomenon are still poorly understood. In this project, the analysis of the electroencephalographic (EEG) event-related desynchronization/synchronization (ERD/ERS) of alpha rhythm (8-12 Hz) has been used as an index of cortical activation or inhibition. High-resolution EEG was recorded from healthy individuals to probe the activation patterns in the sensory-motor cortical areas during unilateral finger movements and electrical sensory stimuli perception under the MVF procedure. The main objective was to propose a neurophysiological model underpinning the illusory experience of the movement and its interaction with sensory stimuli. The first part of the work successfully demonstrated that, as compared to the control condition without MVF, auditory-triggered voluntary unilateral movements of the index finger performed with the MVF illusion were related to a prominent alpha ERD (cortical activity) in the sensory-motor cortical areas ipsilateral to the moving-finger and contralateral to the mirrored-finger. This was true during both movement preparation and execution. Additionally, the analysis of the cortical sources showed as the MVF condition was characterized by a significant alpha ERD in the frontal polar areas during the anticipation of the movement as well as in the premotor, primary sensory-motor, and posterior parietal cortical areas during the illusory experience. The second part of the work investigated the sensory-motor interaction at the cortical level between illusory finger movements and simultaneous actual painful or non-painful electrical stimuli applied to the finger behind the mirror. Results found that MVF was associated with reduced activity of the limbic system, leading to a lower subjective evaluation of the painful stimuli intensity. Several chronic pain conditions derive from dysfunctions in ganglia-thalamo-cortical motor loops. Hence, enhancing the knowledge of the MVF neural correlates may be fundamental to developing MVF-based therapies that stimulate neural plasticity and cortical reorganization in the sensory-motor areas for patients who cannot rely on the correct movement of one limb. Moreover, the MVF-related EEG alpha ERD/ERS might be used as a neurobiomarker for the constant cortical monitoring of the motor recovery trajectory of the patients. Finally, the neurophysiological features underlying the MVF illusory phenomenon may facilitate the EEG-based brain-computer interface application, a technology that avails of EEG alpha ERD/ERS detection to control neurorehabilitation devices.