Related Experiment Video
Updated: Mar 3, 2026
Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
Published on: October 7, 2025
Modulation of motor cortex excitability predicts antidepressant response to prefrontal cortex repetitive transcranial
Albino J Oliveira-Maia1, Daniel Press2, Alvaro Pascual-Leone3
1Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, 02215 MA, USA; Department of Psychiatry and Mental Health, Centro Hospitalar de Lisboa Ocidental, 1349-019 Lisboa, Portugal; NOVA School of Medicine | Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal; Champalimaud Research & Clinical Centre, Champalimaud Centre for the Unknown, 1400-038 Lisboa, Portugal.
Background:
Repetitive transcranial magnetic stimulation (rTMS) targeting the left dorsolateral prefrontal cortex (DLPFC) is a treatment option for patients with medication-resistant major depressive disorder (MDD). However, antidepressant response is variable and there are currently no response predictors with sufficient accuracy for clinical use.
Objective:
We report on results of an observational open-label study to determine whether the modulatory effect of 10 Hz motor cortex (MC) rTMS is predictive of the antidepressant effect of 10 Hz DLPFC rTMS.
Methods:
Fifty-one medication-resistant MDD patients were enrolled for a 10-day treatment course of DLPFC rTMS and antidepressant response was assessed according to post-treatment reduction of the 17-item Hamilton Rating Scale for Depression score. Prior to treatment, we assessed the modulation of motor evoked potential (MEP) amplitude by MC rTMS. MEP's were induced with single TMS pulses and measured using surface electromyography. MEP modulation was calculated as the change of mean MEP amplitude after MC rTMS.
Results:
MEP modulation proved to be a robust predictor of reduction of clinician-rated depression severity following the course of DLPFC rTMS: larger MC rTMS-induced increase of corticospinal excitability anticipated a better antidepressant response. This was found both in univariate analyses (Spearman regression: rho = 0.43, p < 0.005) and a multivariable linear regression model (β = 0.25, p < 0.0001) controlling for baseline depression severity, age and resting motor threshold.
Conclusions:
These findings suggest that MC rTMS-induced modulation of corticospinal excitability warrants further evaluation as a potential predictive biomarker of antidepressant response to left DLPFC 10 Hz rTMS.
