Accelerated Anodal tDCS over Right Inferior Frontal Gyrus Improves Inhibitory Control Across Repeated Sessions: Evidence of a Cumulative After Effect

Background/Objectives: The right inferior frontal gyrus (rIFG) is a key node of the neural network underlying inhibitory control and a promising target for non-invasive brain stimulation. Here, we investigated whether an accelerated anodal transcranial direct current stimulation (tDCS) protocol over the rIFG could produce cumulative improvements in response inhibition. This issue is particularly relevant because cumulative effects of accelerated stimulation cannot be taken for granted, and repeated administrations may lead to progressive improvement, saturation, or no measurable offline persistence. In addition, sham-controlled accelerated studies remain limited. Methods: Twenty-two healthy participants underwent three stimulation sessions within the same day. Inhibitory control was assessed using the Stop-Signal task, while Stop-Signal Reaction Time (SSRT) and mean error rate were analyzed by means of linear mixed-effects models. Results: Results showed a significant effect of time and a significant stimulation-by-time interaction across the three sessions, indicating a progressive reduction in SSRT during the accelerated protocol. Thus, inhibitory control performance improved as stimulation sessions increased. Conclusions: These findings suggest that accelerated anodal tDCS over the rIFG can induce cumulative short-term improvements in inhibitory control. The results support the relevance of the rIFG as a neuromodulation target, while highlighting the importance of interindividual variability and the need for more translationally oriented protocols.