A novel tDCS control condition using optimized anesthetic gel to block peripheral nerve input.

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Transcranial direct current stimulation (tDCS) efficacy may be influenced by peripheral nerve stimulation.
• A need exists for effective control conditions in tDCS research to isolate brain effects.

Purpose of the Study:

• To develop and evaluate a novel topical anesthetic gel (BL10) for blocking peripheral input during tDCS.
• To compare the efficacy and electrical properties of BL10 gel against EMLA and placebo gels.

Main Methods:

• A blinded randomized cross-over study involving 18 healthy volunteers.
• Subjects rated scalp stimulation sensations using a visual analog scale during tDCS with different gels.
• In vitro experiments assessed gel resistivity and temperature changes under direct current.

Main Results:

• Both BL10 and EMLA gels reduced scalp stimulation sensations compared to placebo.
• BL10 gel demonstrated a faster onset of action and lower reported sensations within the first 30 minutes.
• BL10 gel exhibited superior electrical stability, with no significant change in resistivity or temperature under direct current, unlike EMLA gel.

Conclusions:

• Topical anesthetics, particularly the BL10 gel, can effectively mitigate peripheral nerve stimulation during tDCS.
• The BL10 gel offers a more stable and rapid-acting control condition for tDCS research compared to EMLA gel.