Abstract| Volume 16, ISSUE 1, P115, January 2023

TMS-EEG: a window on cortical circuits in severe and focal brain injury

      TMS in combination with EEG (TMS-EEG) enables a direct assessment of the electrophysiological state of cortical circuits with unprecedented degrees of freedom whereby both primary and associative areas can be directly stimulated with a wide range of stimulation parameters. In this way, TMS-evoked potentials (TEPs) can both inform on the local input-output properties of different neuronal population and assess large-scale remote and re-entrant activations within thalamocortical networks. Furthermore, unlike resting EEG-based measures of connectivity, TMS-EEG measures are causal in nature and unconfounded by common inputs or spurious correlations. In my talk, I will first highlight the principles and caveats of TMS-EEG as well as the tools and procedures that can reliably facilitate the acquisition of high-quality TEPs. Then, I will review a series of recent studies in which TMS-EEG was used to probe the state of cortical circuit after brain injury. I will show how measures derived from TEPs can assist the diagnosis of patients with disorders of consciousness, inform on the state of the perilesional cortex after stroke and bear prognostic value for motor recovery and for the subsequent development of delirium. Finally, I will argue that TMS-EEG data can have a key role in driving a paradigm shift in our understanding of the electrophysiological consequences of brain injury and diaschisis.