An Event Related Potential Study Of Reward Circuits And Attentional Bias In Heroin Addicts

Drug addiction is a serious problem which needs to be valued by the country and society.Heroin addicts is a big part of drug addiction group in China.Long-term heroin intake will affect the function of the brain,and cause some difference in cognition and behavior,like reward and attention.However,reward and attention play important roles in the formation of addiction,they are key factors which lead to behaviors like relapsing and drug seeking.In this paper,combined with monetary incentive delay task(MIDT)and Dot probe paradigm,we use event-related potential(ERP)to study the difference and connection in reward processing and attentional bias between heroin addicts and normal people.In MIDT,stimulus with different monetary hints are used as cue,and the followed small square is used as target in order to reveal the effect of different stages and stimulus with different polarity during reward processing.In Dot probe paradigm,addictive images and normal images are used as cues,and the dots which need to be detected are target.It could reflect the attention and its subsequent cognitive impact while facing with drug-related cues.Through the experiment,the main results we find are:1.In MIDT,the behavioral result shows that,in normal people,the reaction time of positive or negative cues are almost same,and both of them are faster than neutral one.But in heroin addicts,the reaction time of positive cues are faster than negative cues than neutral cues.It proves that normal people handle cues with different polarity at same level in reward processing,while the addicts has weakened the role of negative cues.The ERP result shows that,Although the cue-P300,which reveals initial awareness of the reward is similar to normal people.In heroin addicts,amplitude of negative CNV decreases,characteristic of SPN changes,amplitude of FRN increases and feedback-P300 loses the sensibility of negative results.These results indicate that their reward cognition phase from formation of behavior to judgment of behavioral result is different from normal people,especially those parts related to negative monetary reward during this phase.2.In Dot probe paradigm,the behavioral result shows that heroin addicts react faster when addiction pictures and detecting dot are in the same position.It proves that their attentional bias exists.ERP results show that when there are drug related pictures,P1 disappeared and the amplitude of N1 increased significantly in heroin addicts,which means there is some difference in their initial location and distribution of attention.Meanwhile,reflecting attention processing and regulation the amplitude of N2 increased,the latency of P3 evoked by dot advance and late slow component SPW is also different from normal people.All these reflect the attentional bias in heroin addicts have already affected the subsequent cognitive process,like reward.