| Inhibitory control deficit has been regarded as the core cognitive mechanism of high trait impulsivity.Both inhibitory control deficit and high trait impulsivity are closely related to a wide range of problem behaviors and mental disorders.Trait impulsivity refers to a behavioral predisposition towards rapid,unplanned reactions to internal or external stimuli without regard to the negative consequences of these reactions to the impulsive individual or to others.As an important part of cognitive control,inhibitory control refers to the automatic control or suppression of irrelevant stimuli as well as cognitive and behavioral responses,which mainly includes interference inhibition and response inhibition.For a long time,numerous behavioral and neurophysiological studies have explored the relationship between trait impulsivity and inhibitory control,trying to clarify its neural basis of intrinsic activity.However,the results of relative studies are mixed.Some studies have shown that trait impulsivity is significantly correlated with inhibitory control,while others only found a correlation between inhibitory control and a certain dimension of impulsivity or failed to find a stable correlation between these two variables.These results reflect that previous studies have different understandings on the operational definition and selections of assessment tools of trait impulsivity,moreover,different inhibitory control components also correspond to various experimental paradigms.Meanwhile,intraindividual reaction time variability(IIRTV)has been found to be an important indicator which reflected the cognitive fluctuations of executive process in recent years.It has also been regard as a biological marker related to the integrity of the central nervous system,which provided the possibility to further enrich the related results about inhibitory control.As a core component of cognitive control,inhibitory control is also pointed out to be significantly affected by the complexity of external task demands.The processing of interference and conflict stimuli may largely depend on the level and type of load involved in relevant information processing,which should also be taken into account.Furthermore,based on the neurovisceral integration model,the physiological,behavioral,affective and cognitive processes of individual adaptation are based on the bidirectional regulation of autonomic and central nervous systems in the central autonomic network.Specifically,as a physiological indicator of parasympathetic nerve regulation ability,vagus nerve activity is closely related to inhibitory control function.Individuals with poor vagus nerve activity and inhibitory control are more likely to have some problem behaviors and mental disorders which characterized by high trait impulsivity.However,it has not been studied yet whether trait impulsivity individuals have deficits in the connection between autonomic nervous function and central cognitive nervous functionTo solve the above problems,six sub-experiments in three studies has been conducted to investigate the inhibitory control deficit of impulsive individuals and its basis of autonomic and central nervous system activities.In study 1,we evaluated the association between trait impulsivity and the impaired interference inhibition as well as impaired response inhibition respectively.In study 2,we investigated the interaction between vagus nerve activity and inhibitory control on individual trait impulsivity from the perspective of autonomic and central integration,and tried to prove that the high impulsive behaviors is the result of autonomic neural activity deficit and central cognitive function deficit.In study 3,the difference of EEG features in inhibitory control of individuals with high and low level of trait impulsivity was investigated,and the influence of different load conditions on inhibition control processing of individuals with high and low trait impulsivity was further investigated.Study 1 consisted of two behavioral experiments.In experiment 1,the revised Flanker task was used to investigate the interference inhibition of impulsive individuals and its gender differences.Experiment 2 investigate the response inhibition of impulsive individuals and its gender differences through the revised Go No Go task.The level of individual trait impulsivity in both experiments were assessed using the Barratt Impulsivity Scale.The results show that there is no significant gender difference in the level of individual trait impulsivity and the response inhibition.Individuals with high trait impulsivity showed lower accuracy and greater intraindividual response time variability in inhibitory task,indicating that inhibitory control deficit and cognitive fluctuation are more likely exist in individuals with high trait impulsivity.In addition,the defect of interference inhibition and response inhibition were related to different impulsive trait dimensions of impulsive trait.Interference inhibition deficit was more significantly associated with attentional impulsivity,while response inhibition deficit was more significantly associated with motor impulsivity.Study 2 explored the mechanism of vagus nerve activity on impulsivity individuals’ inhibitory control deficit by multi-channel physiological technique.The study including two experiments.Experiment 1 investigated the interaction effect of vagus nerve activity and the interference inhibition assessed by Flanker task on trait impulsivity.Trait impulsivity was measured using the Barratt Impulse Scale;ECG and respiratory data was collected and analyzed at baseline and during the task,thus two indicators(baseline RSA and RSA reactivity)which reflected vagal tone were obtained completely.Experiment 2 investigated the interaction effect of vagus nerve activity and the interference inhibition assessed by Go No Go task on trait impulsivity.Trait impulsivity,baseline RSA and RSA reactivity were measured in the same way as in Experiment 1.The results showed that,for individuals with small RSA withdrawal,there was a significant correlation between trait impulsivity and the cognitive fluctuation in inhibitory control.For individuals with higher baseline RSA,inhibitory control deficit did not predict trait impulsivity significantly.for individuals with small RSA withdrawal,there was a significant correlation between trait impulsivity and the cognitive fluctuation in inhibitory control.For individuals with higher baseline RSA,impaired inhibitory control did not predict trait impulsivity significantly.The results of the two experiments together suggest that vagus nerve activity plays a moderating role between the inhibitory control and trait impulsivity,which also supported that trait impulsivity might be the result of the interaction between inhibitory control and parasympathetic vagus nerve activity.In study 3,ERP technique was used to investigate the temporal features of impulsive individuals’ inhibitory control under different load conditions(load level and load type).The study consisted of two experiments.Firstly,40 male subjects from the high trait impulsivity group and the low trait impulsivity group were screened by the Barratt impulsivity Scale.Experiment 1 investigated the difference of interference inhibition and electrophysiological activity between two impulsivity groups under different load level.Experiment 2 investigated the difference of the response inhibition and the electrophysiological activity between the two groups under different load type.In experiment 1,it was found that compared with the level under low load,induced N2 difference under high load level was smaller.Compared with individuals with low impulsivity,P3 difference induced in high impulsivity individuals was smaller under both load levels.In experiment 2,compared with the emotional load,individuals under non-emotional load showed more negative N2 difference and shorter P3 latency.The P3 difference induced under non-emotional load was larger in low impulsivity individual,but there was no significant difference with its in high impulsivity individuals under emotional load type.These results suggested that increased level of load significantly decreased individuals’ capability of conflict detection and resolution;the increased impulsivity significantly decreased individuals’ capability of interference inhibition and result evaluation.Emotional load significantly increased the processing time of response inhibition,meanwhile,increased the arousal especially for high impulsivity individuals.In conclusion,the current study systematically investigated the inhibitory control of individuals with different levels of trait impulsivity and its autonomic and central nervous system activity.The results showed that high level of trait impulsivity might be the result of the interaction effects of impaired autonomic nervous activity and central cognitive dysfunction,while the level and type of load have important influence on inhibition control processing and performance. |
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