Department of Psychology, University of Southern California, SGM 501, Los Angeles, CA 90089-1061, USA.
Drug Alcohol Depend. 2011 Jul 1;116(1-3):18-23. doi: 10.1016/j.drugalcdep.2010.11.012. Epub 2010 Dec 21.
Brain regions that track value (including the ventral striatum) respond more during the anticipation of immediate than delayed rewards, even when the delayed rewards are larger and equally preferred to the immediate. The anticipatory response to immediate vs. delayed rewards has not previously been examined in association with cigarette smoking.
Smokers (n=35) and nonsmokers (n=36) performed a modified monetary incentive functional Magnetic Resonance Imaging (fMRI) task (Knutson et al., 2000) that included opportunities to win either immediate or delayed rewards. The delayed rewards were larger and equally preferred to the immediate rewards.
Across groups, greater activation was observed in regions previously shown to track value including bilateral ventral/dorsal striatum during the anticipation of immediate relative to delayed rewards. This effect was significantly greater among smokers than nonsmokers within the right ventral striatum. This group difference was driven particularly by low striatal activation among smokers during delayed reward trials.
The general tendency for striatal reward anticipatory activity to be attenuated when rewards are delayed is exaggerated among smokers relative to comparison participants. Among possible explanations of this relationship are that (1) low anticipatory response to delayed rewards is a phenotypic risk factor for smoking and (2) smoking-related neuroadaptations result in reduced recruitment during the anticipation of delayed rewards.
追踪价值的大脑区域（包括腹侧纹状体）在预期即时奖励时的反应比预期延迟奖励时更为强烈，即使延迟奖励更大且与即时奖励同样受到偏好。此前，尚未在与吸烟有关的情况下检查过即时奖励与延迟奖励的预期反应。
吸烟者（n=35）和非吸烟者（n=36）进行了一项经改良的金钱激励功能磁共振成像（fMRI）任务（Knutson 等人，2000 年），其中包括赢得即时或延迟奖励的机会。延迟奖励更大且与即时奖励同样受到偏好。
在整个群体中，在包括双侧腹侧/背侧纹状体在内的先前显示追踪价值的区域中，观察到在预期即时奖励相对于延迟奖励时的激活增加。与非吸烟者相比，吸烟者在右侧腹侧纹状体中的这种效应更为显著。这种群体差异主要是由吸烟者在延迟奖励试验中纹状体的低激活驱动的。
与对照组参与者相比，当奖励延迟时，纹状体奖励预期活动减弱的一般趋势在吸烟者中更为明显。这种关系的可能解释包括：（1）对延迟奖励的低预期反应是吸烟的表型风险因素；（2）与吸烟相关的神经适应性导致在延迟奖励的预期过程中减少招募。
