Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Mannheim, University of Heidelberg, Germany.
Biol Psychiatry. 2010 Apr 15;67(8):745-52. doi: 10.1016/j.biopsych.2009.10.029. Epub 2009 Dec 30.
Drug addiction is characterized by an unhealthy priority for drug consumption with a compulsive, uncontrolled drug-intake pattern due to a disordered motivational system. However, only some individuals become addicted, whereas others maintain regular but controlled drug use. Whether the transition occurs might depend on how individuals process drug relative to nondrug reward.
We applied functional magnetic resonance imaging to measure mesocorticolimbic activity to stimuli predicting monetary or cigarette reward, together with behavioral assessment of subsequent motivation to obtain the respective reward on a trial-by-trial basis, in 21 nicotine-dependent and 21 nondependent, occasional smokers.
Occasional smokers showed increased reactivity of the mesocorticolimbic system to stimuli predicting monetary reward relative to cigarette reward and subsequently spent more effort to obtain money. In the group of dependent smokers, we found equivalent anticipatory activity and subsequent instrumental response rates for both reward types. Additionally, anticipatory mesocorticolimbic activation predicted subsequent motivation to obtain reward.
This imbalance in the incentive salience of drug relative to nondrug reward-predicting cues, in a network that drives motivation to obtain reward, could represent a central mechanism of drug addiction.
药物成瘾的特点是对药物消费的不健康优先排序，由于动机系统紊乱，导致强迫性、无法控制的药物摄入模式。然而，只有一些人会成瘾，而另一些人则保持有规律但受控的药物使用。这种转变是否发生可能取决于个体如何处理药物相对于非药物奖励的方式。
我们应用功能磁共振成像来测量中脑边缘奖赏系统对预测金钱或香烟奖励的刺激的活动，同时对随后获得各自奖励的动机进行行为评估，在 21 名尼古丁依赖和 21 名非依赖、偶尔吸烟的吸烟者中进行了这些研究。
偶尔吸烟者对预测金钱奖励的刺激的中脑边缘奖赏系统反应增强，相对于香烟奖励，他们随后会付出更多的努力来获得金钱。在依赖吸烟者组中，我们发现两种奖励类型的预期活动和随后的工具反应率相等。此外，预期的中脑边缘奖赏系统激活预测了随后获得奖励的动机。
在驱动获得奖励的动机的网络中，药物相对于非药物奖励预测线索的激励价值不平衡，这可能是药物成瘾的一个核心机制。
