Piloting the protocol for a TMS study of the relationship between corticospinal excitability and cortical oscillatory activity during action preparation

Details

Supervisors

Duque, Julie ; Patnaik, Mantosh

Faculty

Faculté des sciences de la motricité

Degree label

Master [120] en sciences de la motricité, orientation éducation physique, à finalité didactique
Master [120] en sciences de la motricité, orientation éducation physique, à finalité didactique

Abstract

enEvery voluntary movement relies on motor preparation to ensure accurate and precisely actions. Preparatory suppression, a decrease in corticospinal excitability (CSE) measured through motor evoked potentials (MEPs) to Transcranial Magnetic Stimulation (TMS) over primary motor cortex (M1), is a robust marker of action preparation. However, its role remains debated : it may reflect inhibitory control, resolving competition between potential actions, or rather result from gain modulation processes facilitating movement initiation. Beta-band cortical oscillations (13–30 Hz), recorded with electroencephalography (EEG), relate to inhibitory control and movement planning, but their link with preparatory suppression is unclear. This Master Thesis aimed to adapt a validated instructed-delay choice reaction time task for simultaneous TMS-EEG recording to investigate this link. Given the ambitious scope, this thesis focused on verifying that the adapted task still elicited preparatory suppression. Eleven healthy participants received TMS over M1 in the new EEG-compatible task; our analyses focused on MEP amplitudes and reaction times (RTs). Results confirm robust preparatory suppression with MEPs reduced to ~80% of the values obtained at baseline. We also observed faster RTs when TMS pulses occurred during movement preparation, especially when MEPs fell on the selected response side. These pilot findings are consistent with prior work and confirm feasibility of combining TMS and EEG.