A role for TMS/EEG in neuropsychiatric disorders

A direct and non-invasive measure of cortical excitability and effective connectivity is now made possible by the recent introduction of a new technique based on the combination of transcranial magnetic stimulation (TMS) and high-density electroencephalography (hd-EEG). This technique allows to directly and non invasively perturb any given cortical area and to simultaneously record, with good spatial and temporal resolution, the excitability and the short and long-range connectivity of the stimulated neurons. Alterations of these parameters of cortical circuits’ functioning have been suggested to underlie the most common neurologic and psychiatric conditions. This review focuses on the advantages of the TMS/hd-EEG technique and its contribution to the evaluation of cortical excitability, effective connectivity changes under physiological and pathological conditions. Moreover, it discusses the main findings of TMS/hd-EEG on cortical oscillatory properties, providing new insights into the neurophysiological underpinnings of neuropsychiatric disorders.