EN
Different brain areas are thought to be integrated into largescale networks. Recent approaches for investigating structural organization and functional coordination within these networks involve measures of connectivity among brain areas. Transcranial magnetic stimulation (TMS) can be used to analyze the functional state of the cerebral cortex, discovering changes in its excitability, connectivity and plasticity which may have occurred through processes such as learning or recovery from a lesion. We review studies using in vivo functional brain connectivity technologies. TMS-EEG studies have begun to describe the nature of the TMS-evoked EEG responses in order to broaden the comprehension of the activation mechanisms of TMS. Several studies have proved the power of TMS-EEG by displaying many data about the excitability or connectivity of the brain. Particularly, it has been proposed that the very first part of the TMS evoked EEG response displays the excitability of the stimulated cortex while its spatio-temporal distribution over the scalp displays the spread of activation to other cortical areas – via intra and inter-hemispheric cortico-cortical connections as well as to sub-cortical structures and spinal cord via projection fibres – that means the effective connectivity of the stimulated area. Finally effective connectivity may be considered as the union of structural and functional connectivity. These studies provide insights into the relationships between brain structure and function.