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All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human welfare and have been reviewed by the local institutional review board.
- Instruct and train participants to self-administer transcranial direct current stimulation (tDCS).
- Show participants an instructive tDCS training video that details the entire step-by-step process of administering the stimulation.
- Ask participants to prepare the headstrap with guidance from study personnel. The headstrap holds the sponge electrodes in position throughout the duration of the stimulation session.
- Have participants attach the sponges, which are pre-moistened with 5mL of saline solution, to the cable electrodes.
- Instruct participants to place the headstrap upon their head, taking care to align the nasion marker on the front of the headstrap with the bridge of their nose.
- Have participants pull the back of the headstrap towards the posterior end of their heads so the back of the headstrap rests over their inion. The dorsolateral prefrontal cortex (DLPFC), left anodal tDCS montage is used.
- Confirm that the participant has achieved optimal or moderate contact quality before continuing.
NOTE: The device dynamically adjusts its voltage depending on the entire resistive path between the anodal and cathodal electrodes (including skin and skull impedance) to deliver consistent amperage. The device will not unlock to release the stimulation if the contact quality is poor or the impedance is too high. - If a participant has a poor or moderate contact quality, then suggest methods to improve contact quality, such as adding saline to the sponges, adjusting headstrap placement, or brushing hair away from electrode sites. The participant can monitor their own contact quality by looking at the device's interface screen.
- Assess the participant's aptitude to complete study procedures to determine whether they understand and can replicate the procedures competently at home.
- Participants complete a tolerability test lasting 90 seconds to determine whether they are able to comfortably tolerate 2.0 mA of direct current. If a participant finds they are unable to handle 2.0 mA, lessen the amperage to 1.5 mA and further to 1.0 mA if deemed necessary. If a participant finds 1.0 mA intolerable, they must be discontinued from the study.