Using a TMS Navigation System for High-Precision Digitization of Sensor Locations to Improve Source Localization.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Signal Processing

Background:

• Accurate source localization in neuroscience relies on precise spatial digitization of sensor locations.
• Existing Transcranial Magnetic Stimulation (TMS) infrastructure, specifically Navigated Brain Stimulation (NBS) systems, is underutilized for electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) sensor digitization.
• Dedicated digitization equipment can be costly, posing a barrier for many research labs.

Purpose of the Study:

• To present a practical, reliable, and cost-effective method for digitizing EEG sensor locations using the Nexstim NBS system.
• To demonstrate how to integrate digitized sensor data into EEG preprocessing and source localization pipelines.
• To improve the spatial accuracy and anatomical relevance of source modeling in EEG and fNIRS studies.

Main Methods:

• Utilizing the Nexstim NBS system's default tools for digitizing EEG electrode positions.
• Exporting coordinate data and processing it using custom Python scripts.
• Integrating digitized data into MNE-Python for source localization, including alignment with MRI images and coregistration optimization.

Main Results:

• The protocol provides a complete workflow from digitization to source estimation.
• Custom Python scripts facilitate coordinate processing and coregistration, ensuring reproducibility.
• Incorporating digitized electrode positions significantly improves the anatomical accuracy and interpretability of cortical source estimates compared to standard electrode montages.

Conclusions:

• The Navigated Brain Stimulation (NBS) system offers a practical solution for accurate EEG sensor digitization.
• Leveraging existing TMS infrastructure reduces the need for specialized digitization equipment.
• This method enhances the reliability and anatomical validity of brain source localization techniques.