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Updated: Dec 24, 2025
Neuroimaging-Guided TMS–EEG for Real-Time Cortical Network Mapping
Published on: June 13, 2025
Probing EEG activity in the targeted cortex after focal transcranial electrical stimulation
Syoichi Tashiro1, Hartwig R Siebner2, Angeliki Charalampaki3
1Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark; Department of Rehabilitation Medicine, Keio University School of Medicine, Tokyo, Japan.
A novel hybrid approach successfully records electroencephalography (EEG) during transcranial electrical stimulation (TES). This method allows researchers to study the immediate effects of TES on brain activity, overcoming previous recording challenges.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Electrophysiology
Background:
- Recording electroencephalography (EEG) concurrent with focal transcranial electrical stimulation (TES) presents significant technical challenges.
- Simultaneous stimulation and recording are crucial for understanding TES effects on neuronal activity.
Purpose of the Study:
- To introduce and validate a hybrid stimulation-recording technique for focal TES.
- To enable direct EEG recording before and after TES in the targeted cortical area.
Main Methods:
- A novel hybrid electrode design integrated an EEG electrode within a double-ring montage for focal TES.
- The combined electrode was positioned at the C3 location of the EEG 10-20 system.
- Neuronal activity was recorded in two volunteers before and after 20 Hz alternating-current TES (1-2 mA), with electric field simulations performed using SIMNIBS.
Main Results:
- The hybrid TES-EEG setup enabled successful EEG recording immediately preceding and following TES.
- Electrical field simulations demonstrated comparable cortical electric fields between pseudomonopolar montages with and without the embedded EEG electrode.
Conclusions:
- The developed hybrid TES-EEG approach provides a viable method for investigating the after-effects of focal TES on cortical neuronal activity.
- This technique facilitates a more comprehensive understanding of brain responses to targeted electrical stimulation.
