HD-tDCS induced changes in resting-state functional connectivity: Insights from EF modeling.

Area of Science:

• Neuroscience
• Neuromodulation
• Psychiatric Research

Background:

• High-definition transcranial direct current stimulation (HD-tDCS) is a promising neuromodulation technique for psychiatric disorders.
• Response variability remains a significant challenge for clinical implementation of HD-tDCS.
• Individualized head models offer a potential solution to mitigate response variability.

Purpose of the Study:

• To investigate the variability of electric fields (EFs) induced by HD-tDCS.
• To assess the impact of HD-tDCS on resting-state functional connectivity (rsFC) across different time windows.
• To explore the relationship between EF magnitude and rsFC variations.

Main Methods:

• A randomized, double-blind, sham-controlled study involving 70 healthy males.
• HD-tDCS applied to the right inferior frontal gyrus (rIFG) while participants underwent resting-state functional magnetic resonance imaging (rs-fMRI).
• Individualized head models and EF simulations were generated; rsFC analyzed using seed-to-voxel analysis with subgroup analysis on EF magnitude and rsFC.

Main Results:

• Significant variability in HD-tDCS-induced EFs was observed.
• Active HD-tDCS increased rsFC between the rIFG and the left prefrontal cortex during and after stimulation compared to sham.
• EF magnitude showed dynamic correlations with rIFG-hippocampus rsFC during stimulation.

Conclusions:

• HD-tDCS can increase prefrontal rsFC, with effects influenced by EF magnitude and stimulation duration.
• Observed high variability in EFs underscores the necessity of individualized HD-tDCS protocols.
• Individualized head models are essential for optimizing HD-tDCS efficacy and reducing response heterogeneity in clinical applications.