Dose-controlled tDCS reduces electric field intensity variability at a cortical target site

Area of Science:

• Neuroscience
• Biomedical Engineering
• Computational Modeling

Background:

• Transcranial direct current stimulation (tDCS) efficacy is limited by variable effects.
• Inter-individual anatomical differences cause inconsistent current delivery in conventional tDCS.
• Individualised dose-control may mitigate tDCS variability by standardizing electric field (E-field) intensity.

Purpose of the Study:

• Characterize E-field intensity variability in the left primary motor cortex (M1) and brain-wide.
• Compare E-field variability between fixed-dose and individualised dose-controlled tDCS.
• Assess the impact of individualised dose-control on tDCS E-field distribution.

Main Methods:

• Utilized the Realistic Volumetric Approach to Simulate Transcranial Electric Stimulation (ROAST) software.
• Simulated tDCS in 50 individual brain scans from the Human Connectome Project.
• Compared fixed-dose (1mA & 2mA) and individualised dose-controlled tDCS targeting left M1.

Main Results:

• Fixed-dose tDCS showed over 100% E-field intensity variation in left M1 across individuals.
• Substantial E-field variation was observed brain-wide with fixed-dose tDCS.
• Individualised dose-control achieved consistent E-field intensity at the left M1 target site.

Conclusions:

• Individualised dose-control effectively eliminates E-field intensity variance at the targeted cortical site.
• This approach holds potential for reducing the known variability in tDCS physiological and behavioral effects.
• Standardizing E-field delivery may enhance the reliability of tDCS as a research and therapeutic tool.