Related Experiment Video
Updated: Oct 17, 2026
Neuroimaging-Guided TMS–EEG for Real-Time Cortical Network Mapping
Published on: June 13, 2025
Individualized TMS-EEG mapping reveals clinically relevant early prefrontal cortical activity in major depressive
Elena Ukharova1, Isabella O'Meeghan2, Ida Granö2
1Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland; Department of Clinical Neurophysiology, HUS Diagnostic Center, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
Objective:
To determine whether individualized TMS-EEG mapping improves assessment of early cortical responses in the dorsolateral prefrontal cortex (DLPFC) compared with conventional Beam F3 targeting and their association with depressive symptom severity.
Methods:
Single-pulse TMS-EEG was performed in 30 patients with major depressive disorder (MDD) and 15 healthy controls. Individualized mapping identified DLPFC stimulation sites and intensities that minimized artifacts while eliciting robust early TMS-evoked potentials (>6 μV within 60 ms). Responses were compared with Beam F3 stimulation at 120% resting motor threshold. Early cortical activity was quantified using global mean field power (GMFP) and region-of-interest (ROI) area-under-the-curve (AUC) during the 10-30 ms post-stimulation interval.
Results:
Individualized mapping produced distinct early cortical responses and significantly smaller early GMFP and ROI AUC responses (q < 0.001) compared to Beam F3 stimulation. Within the MDD group, lower GMFP AUC was associated with greater depression (PHQ-9: ρ = - 0.43, q = 0.046) and anxiety severity (GAD-7: ρ = - 0.58, q = 0.008). Lower ROI AUC was associated with greater depressive symptoms (PHQ-9: ρ = - 0.57, q = 0.008; QIDS-SR: ρ = - 0.48, q = 0.033) and anxiety severity (GAD-7: ρ = - 0.45, q = 0.040). No significant clinical associations were observed for Beam F3-derived measures.
Conclusions:
Individualized TMS-EEG mapping identifies clinically relevant early DLPFC responses not detected using conventional Beam F3 targeting.
Significance:
Individualized targeting improves the sensitivity of prefrontal TMS-EEG and may enhance detection of early cortical responses associated with depressive and anxiety severity.
