How does the electric field induced by tDCS influence motor-related connectivity? Model-guided perspectives

Area of Science:

• Neuroscience
• Computational modeling
• Brain stimulation

Background:

• Transcranial direct current stimulation (tDCS) is increasingly used to modulate brain activity and connectivity.
• Multi-electrode montages are replacing simpler tDCS protocols for targeting neural networks.

Purpose of the Study:

• Investigate electric field (EF) patterns from tDCS protocols designed to alter functional brain connectivity.
• Analyze EF characteristics in relation to functional connectivity outcomes.

Main Methods:

• Selected existing tDCS studies targeting motor-related connectivity.
• Performed computational simulations of induced EF in five head models.
• Analyzed EF magnitude and orientation in motor cortical regions.
• Qualitatively assessed functional connectivity outcomes against EF and protocol parameters.

Main Results:

• EF patterns predicted by computational models correlate with tDCS's ability to modulate functional brain connectivity.
• Observed regional differences in EF distribution across subjects, informing electrode placement variability.
• EF characteristics can guide the optimization of tDCS for specific connectivity outcomes.

Conclusions:

• tDCS-induced neuronal modulation can influence intra- and inter-hemispheric connectivity within motor networks.
• Computational modeling is crucial for optimizing tDCS dosing and electrode placement for clinically relevant connectivity modulation.