Department of Psychology, Clemson University, 418 Brackett Hall, Clemson, SC, 29634, USA.
Department of Psychological and Brain Sciences, Texas A and M University, 400 Bizzell St., College Station, TX, 77843, USA.
Drug Alcohol Depend. 2019 Jan 1;194:518-525. doi: 10.1016/j.drugalcdep.2018.11.014. Epub 2018 Dec 3.
Substance use problems are often characterized by dysregulation in reward sensitivity and inhibitory control. In line with this representation, the goal of this investigation was to determine how substance abuse tendencies among university students affect incentivized response inhibition. Additionally, this study examined whether striatal dopamine moderates the impact of substance use on response inhibition performance.
The sample included ninety-eight university students. Participants completed this prospective experimental study at an on-campus laboratory. All participants completed substance abuse and disinhibition subscales of the Externalizing Spectrum Inventory-Brief Form. Using a within-subjects design, participants then performed the Stop Signal Task under both neutral (unrewarded) and reward conditions, in which correct response cancellations resulted in a monetary reward. Striatal tonic dopamine levels were operationalized using spontaneous eyeblink rate.
The outcome measures were Stop Signal Reaction Time (SSRT) performance in the unrewarded and rewarded phases of the task. A hierarchical linear regression analysis, controlling for trait disinhibition, age, gender, and cigarette smoking status, identified an interactive effect of substance use and striatal dopamine levels on incentivized SSRT. Substance abuse tendencies were associated with slower SSRT and thus poorer inhibitory control under reward conditions among individuals with low levels of striatal dopamine (F = 7.613, p = .007).
This work has implications for research examining advanced drug use trajectories. In situations in which rewards are at stake, drug users with low tonic dopamine may be more motivated to seek those rewards at the expense of regulating inhibitory control.
物质使用问题通常表现为奖励敏感性和抑制控制的失调。根据这一表现，本研究旨在确定大学生物质滥用倾向如何影响激励反应抑制。此外，本研究还检验了纹状体多巴胺是否调节了物质使用对反应抑制表现的影响。
该样本包括 98 名大学生。参与者在校园实验室完成了这项前瞻性实验研究。所有参与者都完成了外部表现清单-简短形式的物质滥用和去抑制子量表。然后，参与者采用内隐设计，在中性（无奖励）和奖励条件下完成停止信号任务，在正确反应取消时会获得金钱奖励。纹状体紧张多巴胺水平通过自发眨眼率来实现。
测量指标为任务无奖励和奖励阶段的停止信号反应时间（SSRT）表现。一项分层线性回归分析，控制了特质去抑制、年龄、性别和吸烟状况，确定了物质使用和纹状体多巴胺水平对激励性 SSRT 的交互作用。物质滥用倾向与较慢的 SSRT 相关，因此在纹状体多巴胺水平较低的个体中，奖励条件下的抑制控制较差（F=7.613，p=0.007）。
这项工作对研究高级药物使用轨迹具有启示意义。在有奖励的情况下，纹状体多巴胺水平低的药物使用者可能更有动力为了获得奖励而不惜牺牲抑制控制。
