Neuromodulation of inhibitory control using phase-lagged transcranial alternating current stimulation.

The participants were 24 healthy volunteers, so the study does not show what would happen in patients. There was no sham stimulation condition, so the comparison was between two active phase patterns rather than real stimulation versus placebo-like stimulation. The authors state that scalp-based tACS could not effectively stimulate deep structures such as the dorsal anterior cingulate cortex. The simulated electric field at the cortex was 0.11 ± 0.02 V/m, which the authors note is below the 0.2 V/m they cite as needed to modulate neurons in awake and behaving mammals. EEG was recorded after stimulation sessions because tACS noise contaminated EEG during stimulation, so the neural measures may reflect aftereffects rather than direct online stimulation. In-phase and out-of-phase sessions were given in sequence with at least a 10-minute gap, and although order was counterbalanced, possible carryover effects remain uncertain.

Funding was provided by the National Research Foundation of Korea.

Do not read this as evidence that tACS improves inhibitory control in patients. The participants were healthy adults, no sham condition was used, and the authors say the stimulation may not have effectively reached the deep dorsal anterior cingulate target.