Modern and integrated technologies in evaluating post-lesion brain plasticity

In the last decade, new techniques of cerebral non-invasive functional imaging have attempted to gain a deeper insight to in the biological mechanism subtending clinical recovery and the plastic phenomena, investigating different aspects of functional neuroanatomy and neurophysiology. Nevertheless, brain mapping method has limited performance in terms of temporal (fMRI, PET) or spatial (MEG, EEG) resolution. Moreover, recent studies evidenced that in stroke patients, fMRI, the mostly utilized mapping technique, may fail to detect neural activation and consequently, to comprehensively describe the sites and the amount of task specific neuronal activation. On this basis, functional imaging with high spatialtemporal resolution requests integration of information derived from different acquisition modalities until new technologies will be available. So far, functional topographical studies evidenced inter-hemispheric activation asymmetries following mono-hemispheric stroke and an extensive involvement of supplemental areas to achieve even simple tasks. However, functional neuroimaging do not exhaustively explore the mechanisms subtending plastic phenomena; therefore a complete investigation of cerebral plasticity should include a neurophysiologic study of stroke patients. Recent studies underlined that the changes in the intracortical inhibition (1C1) and facilitation (ICF) in the affected and unaffected hemispheres may play a relevant role in determining neural plastic reorganization in stroke patients.