Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Transcranial direct current stimulation (tDCS) effectiveness varies due to electrode positioning.
• Understanding the impact of positioning errors is crucial for reliable tDCS outcomes.

Purpose of the Study:

• To investigate how electrode positioning errors affect current flow in tDCS.
• To compare these effects across tDCS set-ups with varying focality.

Main Methods:

• Utilized 240 datasets from an experimental study using conventional and focal tDCS during MRI.
• Performed individualized electric field modeling comparing planned vs. actual electrode positions.
• Quantified the impact of positioning errors on electric field dose in target regions.

Main Results:

• Focal tDCS montages showed higher planned current dose (7-12%) compared to conventional.
• Electrode positioning errors significantly reduced current flow in target regions, particularly for focal tDCS (26-30%).
• Dose reductions were substantially larger for focal (29-43%) versus conventional tDCS set-ups.

Conclusions:

• Accurate electrode positioning is critical for focal tDCS to maintain current dose in target regions.
• Methods to improve electrode placement, minimize drift, and verify positions are essential.
• Positioning errors must be considered in tDCS dose-response studies, especially for focal applications.