Enhancing response inhibition through a novel tES-fNIRS framework

Transcranial electrical stimulation (tES) is considered a potentially efficacious technology to modulate response inhibition, but few studies have compared different paradigms and clarified their neurophysiological mechanisms. Thus, to investigate the effects of transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) on the right inferior frontal gyrus (IFG) for improving response inhibition in healthy male adults, simultaneously using fNIRS to monitor prefrontal cortex (PFC) hemodynamic changes during tES intervention. A total of 229 healthy participants were randomly divided into tACS, tDCS and sham groups. Results demonstrated that a significant interaction with regard to the Stroop effect (F _(2,102) = 4.144, P = 0.019, η_p² = 0.075). The post-test result of tACS (70.125 ± 43.435) was significantly greater than that of tACS (65.338 ± 45.500). fNIRS revealed tDCS uniquely reduced oxy-Hb concentration in the prefrontal cortex (Channels 7/10: Ps < 0.05). Both tDCS and tACS can significantly reduce the Stroop effect, indicating that both interventions can improve the response inhibition ability. Additionally, tDCS could enhance neural efficiency by reducing the neural resources required to complete the task, particularly highlighting the phenomenon of shifted neural benefits observed during right IFG stimulation. These findings contribute novel insights into understanding the mechanisms underlying enhanced response inhibition through the application of tES techniques, thereby establishing a foundation for future applications in neurological disorder treatments.