Cranial electrode placement can target both auditory cortices homophasically with matched circuits

Evidence

To facilitate homophasic stimulation in both auditory cortices (target regions), two approximately equivalent circuits were generated using two stimulator systems (Neuroconn, Ilmenau, Germany): Prior electric field simulations suggested that placing the stimulation electrodes at position T7 and T8, and the return electrodes close to position Cz, would produce relatively strong currents in the target regions. The same sinusoidal current (frequency: 4 Hz, starting phase: 0°) was applied to each lateralized circuit, the return electrodes were coupled, and the skin was prepared so that the leftand right-lateralized circuit impedances were matched, while keeping the net impedance below 10kΩ. Current strength was set individually to the point where participants reported being comfortable with receiving tACS under all electrodes. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4777

To facilitate homophasic stimulation in both auditory cortices (target regions), two approximately equivalent circuits were generated using two stimulator systems (Neuroconn, Ilmenau, Germany): Prior electric field simulations suggested that placing the stimulation electrodes at position T7 and T8, and the return electrodes close to position Cz, would produce relatively strong currents in the target regions. The same sinusoidal current (frequency: 4 Hz, starting phase: 0°) was applied to each lateralized circuit, the return electrodes were coupled, and the skin was prepared so that the leftand right-lateralized circuit impedances were matched, while keeping the net impedance below 10kΩ. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4777

Categorization

• DEFINE: Clarifies the tACS montage: what ‘homophasic’ stimulation means and how electrode geometry (T7/T8 vs Cz) targets auditory cortex.
• XREF: Connects to methods for transcranial electrical stimulation protocols; auditory cortex targeting via 10-20 system positions.
• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 4777