Inter-area communication within the motor network: Prestimulus functional connectivity predicts TMS-evoked response

Connectivity patterns play a key role for brain functioning, and the importance of neural oscillations in ensuring communication between distant brain regions is well established. The combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG) has been proposed as a promising tool in the study of effective connectivity, by unravelling neural dynamics and signal propagation following the TMS pulse. It is believed that TMS-evoked potentials (TEPs) reflect the spread of neural activation from the stimulated area to interconnected regions. However, current literature lacks a clear characterization of TEP components, even in the most studied motor network, and it is still unclear whether they reflect functional connectivity at the time of stimulation. In the present study, we aimed at characterizing neural response to TMS in the motor network as a measure of effective connectivity, by investigating the relationship between EEG prestimulus cortico-cortical phase synchronization and TEPs.