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Drug related cue-induced reactivity plays a significant role in maintaining drug use and relapse in addicted individuals. The activation of Dorsolateral striatum-Sensorimotor system (DLS-SM) has been suggested as an important route through which drug cues may induce automatic drug using behavior. The current study used fMRI to investigate the reactivity of heroin abstinent individuals to different types of cues, to clarify the characteristics of the cues that induce the activation of the sensorimotor area. Forty heroin-dependent abstinent individuals and 29 healthy subjects were recruited to perform the heroin cue-reactivity task during fMRI. The participants’ subjective craving and physical signs were evaluated before and after scanning. Whole-brain analysis showed that compared to drug use tool and drug cues, cues related to drug use action were more likely to activate posterior central gyrus, para-hippocampus, supra marginal gyrus, superior parietal lobule (SPL) and inferior parietal lobule (IPL). These areas are involved in motor preparation and output, indicating that the sensorimotor area is also an important neural basis of craving and automatic drug using behavior, and may mediate craving and drug seeking behavior. Our findings thus suggest that cues related to drug using action may induce automatic drug seeking behavior more than cues related only to the drug itself.

Persons who are addicted are known to show cue-induced responses (such as psychological craving) to drug-related cues. Previous research showed that both tool-related (e.g., syringe) and action-related (e.g., use of the syringe) drug cues can elicit craving. However, whether the two types of drug related cues can elicit the same brain reactivity and similar degree of disinhibition is still unclear, especially because of the scarcity of ERP studies on this topic. Using a behavioral task and the ERP technique, the present study investigated the behavior reactivity and EEG characteristics shown by men addicted to heroin and healthy controls in response to tool-related and action-related drug cues.Participants were 36 men, 19 of whom were addicted to heroin and 17 of whom were healthy non-drug users, matched on age and years of education. Participants engaged in the two-choice Oddball task, which included two conditions: A. the tool condition, with a picture of a "cup" serving as the standard stimulus and pictures of drug-use tools serving as deviant stimuli; B. the action condition, with a picture of "drinking water" serving as the standard stimulus and pictures of drug-use actions serving as deviant stimuli. In this experiment, the probabilities of standard stimuli and deviant stimuli were 70% and 30%. Participants were asked to press different keys on the keyboard in response to standard stimuli and deviant stimuli as rapidly and accurately as possible.Behavioral results indicated that in men who were addicted to heroin, greater disinhibition was seen in a longer reaction time in response to action cues than tool cues. Between-group analyses of the ERP data showed that compared to the healthy controls, men who were addicted to heroin demonstrated a smaller N2 and larger P3 amplitude in response to drug related cues. Moreover, action cues elicited a smaller N2 amplitude in the heroin addicted group than the control group, especially in the frontal, central and central-parietal areas of the brain, and a larger P3 amplitude, especially in the central and parietal areas of the brain. Within-group analyses in just the heroin addicted group showed that the N2 was smaller in response to action cues versus tool cues. Meanwhile, the action cues elicited a larger amplitude of P3 than the tool cues, especially in the central, central-parietal and parietal regions of the brain.These findings provide behavioral and ERP evidence for the hypothesis that different types of drug-related cues produce different cue-induced reactivity. More specifically, drug use action stimuli, which appear to trigger greater disinhibition and greater ERP reactivity in the brain areas associated with motor resonance, should be considered in the treatment of addiction and in relapse prevention.

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