Effects Of Dual-Site Transcranial Alternating Current Stimulation On Response Inhibition And Its Neural Mechanism

Background:Response inhibition is an important component of cognitive control.Previous neuroimaging studies have found that inhibitory control cortical networks associated with response inhibition,including the right inferior frontal gyrus（rIFG）,the pre-supplementary motor area（pre SMA）and primary motor cortex（M1）.In addition,neural oscillatory activity in theβband（13-30 Hz）is thought to reflect communication in the rIFG-M1 brain network or rIFG-pre SMA brain network.Relevant evidence suggests that information exchange within or between networks is achieved by oscillatory synchronization of neuronal activity.However,the causal role of cortical networkβsynchrony in response inhibition remains unclear.In recent years,dual-site transcranial alternating current stimulation（dual-site t ACS）has been widely used to investigate the causal relationship between cortical brain network oscillatory activity and cognitive function.The aim of this study was to investigate the effects of dual-site t ACS acting on the rIFG-M1 brain network or the rIFG-pre SMA brain network on response inhibition in healthy adults,and the causal relationship betweenβ-synchrony and response inhibition in these two cortical brain networks.Methods:This study employed a double-blind randomized,multi-group,and replicated experiment design.A total of 180 healthy college students were recruited.Experiment 1included 140 healthy participants randomly assigned to six groups:in-phase dual-siteβ-t ACS applied to the rIFG-M1 brain network group,in-phase dual-siteβ-t ACS applied to the rIFG-pre SMA brain network group,anti-phase dual-siteβ-t ACS applied to the rIFG-M1 brain network group,anti-phase dual-siteβ-t ACS applied to the rIFG-pre SMA brain network group,sham stimulation group,and a control group with t ACS stimulation targeting the left supraorbital area.To validate the main findings of Experiment 1,40healthy participants participated in Experiment 2 and were randomly divided into three groups,including in-phase dual-siteβ-t ACS applied to the rIFG-M1 brain network group,in-phase dual-siteβ-t ACS applied to the rIFG-pre SMA brain network group,and a sham stimulation group.The stop-signal task（SST）was completed during and after 20 min t ACS.Each stop signal task included two blocks.A 5 minutes open-eye resting-state electroencephalography was recorded before and after the t ACS.Subjects completed the Barratt Impulsiveness Scale for recording the subject’s impulsiveness.Results:Firstly,compared to sham stimulation,in-phase dual-siteβ-t ACS applied to the rIFG-M1 brain network(F_1,43=6.66,p=0.01,η_p²=0.13)or the rIFG-pre SMA brain network(F_1,43=6.14,p=0.02,η_p²=0.13)significantly improved stop-signal reaction time（SSRT）,while both anti-phase dual-siteβ-t ACS groups did not show improvement.Furthermore,the improvements in SSRT in both in-phase dual-siteβ-t ACS groups(rIFG-M1:F_1,23=4.58,p=0.04,η_p²=0.17;rIFG-pre SMA:F_1,23=4.46,p=0.05,η_p²=0.16)were validated in Experiment 2.Secondly,the improvement in SSRT in both in-phase dual-siteβ-t ACS groups originated from participants with longer baseline SSRT.Moreover,the improvement in SSRT was associated with individual attentional impulsiveness（rIFG-M1:r=-0.53,p<0.001;rIFG-pre SMA:r=-0.33,p=0.04）and participants with higher attentional impulsiveness showed more improvement in SSRT after the in-phase dual-siteβ-t ACS intervention.Finally,we found that post-stimulation,functional connectivity increased in both in-phase dual-siteβ-t ACS groups(rIFG-M1:F_1,63=5.23,p=0.03,η_p²=0.08;rIFG-pre SMA:F_1,55=5.51,p=0.02,η_p²=0.09)compared to sham stimulation,indicating enhanced communication between brain regions.Conclusion:We demonstrate the effectiveness of dual-site t ACS in enhancing SSRT,suggesting an important role forβactivity of inhibitory control cortical networks in enhancing response inhibition.Furthermore,while exploring the neural mechanisms of response inhibition,and found that participants with lower baseline levels of response inhibition and higher attentional impulsiveness improved their response inhibition more after the intervention.The present study explored the effects of dual-siteβ-t ACS on response inhibition in healthy individuals,further contributing to understand the neural mechanisms of response inhibition.It also provides a potential new therapeutic approach for patients with clinical deficits in response inhibition.