Transcranial Evoked Potentials Can Be Reliably Recorded with Active Electrodes.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Signal Processing

Background:

• Transcranial magnetic stimulation-electroencephalography (TMS-EEG) is crucial for studying brain activity.
• Traditionally, passive electrodes (PE) are used, but active electrodes (AE) offer potential advantages like reduced noise and easier preparation.
• A systematic comparison of AE and PE in TMS-EEG has been lacking.

Purpose of the Study:

• To systematically compare the performance of active electrodes (AE) versus passive electrodes (PE) for recording TMS-evoked EEG potentials (TEPs).
• To evaluate amplitude, topography, and waveform similarity of TEPs recorded with AE and PE.
• To assess the efficiency of both systems in approximating TEPs with fewer trials.

Main Methods:

• Healthy subjects underwent TMS-EEG recordings using both AE and PE systems in separate sessions.
• Stimulation targeted the left primary motor cortex and right medial prefrontal cortex.
• Two artifact removal techniques (ICA and SSP-SIR) were applied, and TEPs were analyzed for amplitude, topography, and similarity (CCC).

Main Results:

• No significant differences in TEP amplitude or topography were observed between AE and PE recordings.
• Concordance correlation coefficients (CCC) indicated high similarity between AE and PE, with only minor discrepancies at a few electrodes.
• Both systems demonstrated comparable ability to approximate final TEP waveforms using a reduced number of trials.

Conclusions:

• Active electrodes (AE) are a viable and effective solution for TMS-EEG recordings.
• AE provide comparable signal quality to PE for TEPs, offering potential benefits in usability.
• The findings support the adoption of AE in TMS-EEG research and clinical applications.