Effects Of Transcutaneous Auricular Vagus Nerve Stimulation On Inhibitory Control And Its Mechanism

Inhibitory control functions play an extremely important role in our daily lives.Inhibition of attention is needed to focus limited cognitive resources on a target task;inhibition of memory is needed to slow or stop negative emotions from intruding;and inhibition of behavior is needed to be more determined to carry out our learning or fitness plans.Inhibitory control,a core component of executive function,helps individuals to behave adaptively in the face of complex and changing environmental challenges by inhibiting internal and external stimuli that are unrelated to the desired goal.In addition,inhibitory control is a fundamental cognitive mechanism that is linked to higher cognitive functions such as reading comprehension,fluid intelligence,and reasoning plans.In recent years,researchers have used cognitive training and non-invasive neuromodulation techniques to improve individuals’ inhibitory control,and transcutaneous auricular vagus nerve stimulation(ta VNS),as a novel,non-invasive neural electrical stimulation technique,has the advantages of being simple to use,portable,safe and tolerable,and cost-effective,and has good potential and value in improving and enhancing individuals’ inhibitory control functions.Therefore,this study was conducted to investigate the effects of ta VNS on individual inhibitory control function and its mechanism of action using healthy university students.Study 1 selected healthy university student subjects to examine the effects of ta VNS on resting-state EEG rhythms in healthy subjects in order to explore neurophysiological evidence for the cognitive effects of ta VNS and to provide a basis for subsequent clarification of the relationship between ta VNS and inhibitory control.Study 2 used a combined Flanker-Go/Nogo experimental task to examine the effect of ta VNS on inhibiting control components in terms of interference inhibition and behavioral inhibition.Study 3 built on Study 2 by using the AX-CPT task to further explore the effects of ta VNS on individuals’ use of inhibitory control styles(i.e.,proactive and reactive inhibition),to attempt to clearly explain how ta VNS modulates inhibitory control.The main findings of the three studies were as follows:Study 1 found that resting-state EEG rhythms differed between individuals in different stimulation conditions(active or sham stimulation).ta VNS increased the absolute power in the Theta band in the frontal region,but no significant differences were seen in the sham stimulation condition,and that oscillations in the Theta band were closely related to inhibitory control function,providing neurophysiological evidence that ta VNS modulates inhibitory control.Study 2 found that on the combined Flanker-Go/Nogo experimental task,subjects received the active ta VNS stimulation showed greater P3 d wave amplitude on both differential wave indicators representing behavioral inhibition and interference inhibition compared to the sham stimulation,suggesting a positive modulatory effect of ta VNS on the components of inhibitory control.Study 3 found that in the AX-CPT task,ta VNS active stimulation evoked significantly higher P3 wave amplitudes than sham stimulation on letter type B,whereas the N2 wave amplitudes evoked by the two stimulus conditions were not significantly different.This indicates that ta VNS has different regulatory effects on inhibition control modes,mainly improving proactive inhibition.The above findings suggest that ta VNS positively modulates the components of inhibitory control(interference inhibition,behavioral inhibition)in individuals;at the same time,ta VNS also facilitates neural circuits related to goal maintenance and contextual updating,thus influencing the way individuals use inhibitory control and enhancing proactive inhibition.Currently,the effects of ta VNS on inhibitory control have been less studied and the findings are not very consistent.The present study not only examined the modulatory effects of ta VNS on inhibitory control,but also explored and explained the cognitive effects of ta VNS from the perspective of inhibitory control modality,which provides some reference for future studies.In addition,ta VNS is expected to play a positive role in inhibitory control interventions as a non-invasive,safe,economical and portable neural electrical stimulation modulation technique.