Exploring the spatial resolution of TMS-EEG coupling on the sensorimotor region

Area of Science:

• Neuroimaging
• Computational Neuroscience
• Brain Mapping

Background:

• Transcranial Magnetic Stimulation combined with Electroencephalography (TMS-EEG) is a promising neuroimaging technique.
• While TMS-EEG offers high temporal resolution, its spatial resolution remains largely undetermined.
• Understanding the spatial resolution is crucial for accurate functional brain exploration.

Purpose of the Study:

• To investigate the spatial resolution of TMS-EEG coupling.
• To determine the minimal distance between stimulated cortical sites that yields distinct response dynamics.
• To evaluate how distance and Brodmann areas influence TMS-EEG spatial resolution.

Main Methods:

• TMS-EEG was applied to the sensorimotor cortex in 20 participants.
• A stimulation grid with targets 10-15 mm apart was used.
• Dynamical signatures of evoked responses were analyzed using regression scores and mixed models.

Main Results:

• Significant differences in dynamical signatures were observed between closely spaced stimulated sites (around 10 mm).
• Shared dynamical signatures extended up to 25-30 mm, decreasing with distance.
• Spatial resolution was anisotropic, being higher across Brodmann areas than within them.

Conclusions:

• TMS-EEG coupling possesses a spatial resolution of at least 10 mm.
• The technique demonstrates anisotropic spatial resolution, influenced by cortical architecture and TMS electric field.
• TMS-EEG is an accurate method for meso-scale brain mapping.