| Object:Addiction is one of the most concerning problems across centuries in the globe.Trying to understand the mechanism of addiction can be helpful for clinical treatment.The previous study have confirmed that impulsivity was the key point for addiction research.Impulsivity,including trait impulsivity and functional impulsivity（could be divided into impulsivity choice and impulsivity action）,was related to all kinds of drug addiction.For now,the unknown question is what could induce the impulsivity of addicts.Drug-related cue-induced reactivity,which can be divided into two different ways of expression:automatic drug-using behavior and craving,occurred at the same stage as the functional impulsivity at the development of addiction.It involved typical feature of impulsivity action:unconscious and automated behavior.Therefore,we surmised drug-related cues could induce impulsivity especially the impulsivity action.Methods:We recruited 16 heroin addicts and 14 healthy controls for this study.Self-reporting,physiological measurement（including heart rate,blood pressure,temperature,and skin electricity）,behavior experiment,and fMRI were used for the assessment.We chose BIS-11 and S-UPPS-P to assess the trait impulsivity of participants;The physiological measurement was measured at before and after the fMRI scans;Lying in the MRI machine,participants need to finish the Go/NoGo task composed by drug-related pictures.Meanwhile,the BOLD signal was observed by the fMRI.SPSS 20.0 was selected for the analysis of the data.For fMRI,we used Dpabi and SPM to analyze the data and perform ANOVA for repeated measurement.Marsbar was used for simple effect analysis further.All activated brain areas were presented by Brain Net Viewer.FWE correction in cluster level was adopted and the threshold set as 0.05.Results:（1）There was no significant difference between the heroin addiction group and the healthy control group in the scores of trait impulsivity scale;（2）Compared with the healthy control group,the heart rate of heroin addicts significantly decreased after the fMRI scans（p<0.001）,and there was no significant difference in body temperature,blood pressure,skin electricity,and VAS scores;（3）For Go/NoGo,the response time of the heroin addiction group was significantly longer than that of the healthy control group（p=0.067）,and the response accuracy of the heroin addiction group was significantly higher than that of the healthy control group（p=0.004）.The attention of the heroin addicts was affected by drug-related clues.（4）On the fMRI,it was found that when the heroin addicts completed the Go/NoGo task,the brain regions such as the posterior central gyrus(p FWE<0.001),the putamen(p FWE<0.05),the insula(p FWE<0.05),and the pallidum(p FWE<0.001)were significantly activated;（5）Bold signal values in brain regions such as the olfaction cortex（r=-0.61,p<0.05）,the putamen（r=-0.74,p<0.01）,the superior frontal gyrus（r=-0.67,p<0.01）,and the pallidum（r=-0.60,p<0.05）were significantly correlated with scores of trait impulsivity in the heroin-addiction group.Conclusion:Heroin addicts may not have high trait impulsivity,but they may have impulsivity action induced by drug-related cues after long-term drug-using.At the same time,the dorsolateral striatum plays a role in generating the habitual and automatic drug-seeking tendency under the drug-related cues.SM-DLS plays an important role in this process.Besides,the insula is an important neural basis for craving in heroin addicts.The essence of impulsivity action is cue-induced reactivity.Finally,our research suggests that trait impulsivity such as sensation seeking share the common neural basis with impulsivity action in heroin addiction. |
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