Effects of Electrode Drift in Transcranial Direct Current Stimulation

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Physics

Background:

• Conventional transcranial direct current stimulation (tDCS) uses saline-soaked sponges and elastic straps for electrode placement.
• Electrode displacement during tDCS sessions can occur due to inadequate preparation.

Purpose of the Study:

• To investigate the impact of electrode drift on electric field distribution in conventional tDCS.
• To analyze how electrode movement affects current intensity in brain structures.

Main Methods:

• Utilized MRI-derived finite element models to simulate electric fields from tDCS.
• Examined two common electrode montages: M1/SO and F3/F4.
• Quantified current intensity in 20 brain structures under varying degrees of electrode drift.

Main Results:

• A 5% incremental drift in electrode position significantly altered tDCS current distribution in both M1/SO and F3/F4 montages.
• Even minimal electrode drift (5%) resulted in significant differences in current intensity across various brain structures.
• Statistical analysis confirmed the significant impact of electrode drift on current delivery (P < 0.001).

Conclusions:

• Electrode position drift during tDCS significantly changes the intensity of brain stimulation.
• Minimizing electrode drift is essential for improving the reproducibility and interpretability of tDCS studies.
• Quantifying and statistically addressing electrode drift may enhance the characterization of tDCS effects on brain function and behavior.