TMS-Induced Modulation of EEG Functional Connectivity Is Affected by the E-Field Orientation

Area of Science:

• Neuroscience
• Cognitive Science
• Biophysics

Background:

• Transcranial magnetic stimulation (TMS) and electroencephalography (EEG) coregistration enables non-invasive brain circuit analysis.
• TMS generates an electric field (E-field) to induce brain activation, while EEG records the resulting electrical activity.
• Investigating brain functional connectivity is a key application of combined TMS-EEG.

Purpose of the Study:

• To determine how TMS E-field orientation affects the spatial pattern and strength of brain functional connectivity.
• To explore the specificity of E-field orientation in modulating cortex-based neural responses.

Main Methods:

• Systematic alteration of TMS E-field orientation during stimulation of the left pre-supplementary motor area.
• Utilizing coregistered TMS-EEG to measure changes in brain electrical activity and functional connectivity.
• Analyzing the topography and intensity of functional connectivity changes in response to varying E-field orientations.

Main Results:

• Stimulating the left pre-supplementary motor area with TMS increased functional connectivity in areas related to the primary motor cortex.
• A distinct modulation of functional connectivity intensity was observed, dependent on the TMS E-field orientation.
• The findings highlight the importance of E-field orientation for targeted brain stimulation effects.

Conclusions:

• TMS E-field orientation is a critical parameter that significantly influences brain functional connectivity.
• The study demonstrates orientation-specific modulation of motor cortex functional connectivity by TMS.
• Optimizing TMS E-field orientation is essential for precise and effective non-invasive brain probing.