A novel approach to modulating response inhibition: Multi-channel beta transcranial alternating current stimulation

Deficits in response inhibition are associated with numerous psychiatric disorders. Previous studies have revealed the crucial role of the right inferior frontal gyrus (rIFG), pre-supplementary motor area (preSMA), and beta activity in these brain regions in response inhibition. Multi-channel transcranial alternating current stimulation (tACS) has garnered significant attention for its ability to modulate neural oscillations in brain networks. In this study, we employed multi-channel tACS targeting rIFG-preSMA network to investigate its impact on response inhibition in healthy adults.

In Experiment 1, 70 healthy participants were randomly assigned to receive 20 Hz in-phase, anti-phase, or sham stimulation over rIFG-preSMA network. Response inhibition was assessed using the stop-signal task during and after stimulation, and impulsiveness was measured via the Barratt Impulsiveness Scale. Additionally, 25 participants received stimulation at the left supraorbital area to account for potential effects of the "return" electrode. Experiment 2, consisting of 25 participants, was conducted to validate the primary findings of Experiment 1, including both in-phase and sham stimulation conditions, based on prior estimations derived from the results of Experiment 1.

In Experiment 1, we found that in-phase stimulation significantly improved response inhibition compared with sham stimulation, whereas anti-phase stimulation did not. These findings were consistently replicated in Experiment 2. We also conducted an exploratory analysis of the multi-channel tACS impact, revealing that its effects primarily emerged during the post-stimulation phase. Furthermore, individuals with higher baseline attentional impulsiveness showed greater improvements in the in-phase stimulation group.

These results demonstrate that in-phase beta-tACS over rIFG-preSMA network can effectively improve response inhibition in healthy adults and provides a new potential treatment for patients with deficits in response inhibition.