PNAS：科学家发现吸烟者犯烟瘾的机制

最近，日本和加拿大研究人员近日在美国《国家科学院学报》网络版上报告说，他们发现吸烟者犯烟瘾时，想吸烟的欲望是脑部的前额区两个部位共同作用产生的。

上述成果源自日本理化研究所分子成像科研中心和加拿大麦基尔大学蒙特利尔神经学研究所的试验及分析结果。

研究者邀请总共10名男女烟民提供合作，设定了试验后可吸烟和不能吸烟两种状况，然后让他们看吸烟录像。借助功能性磁共振成像，研究人员观察分析在这两种情况下视觉刺激诱发吸烟欲望时，烟民大脑活动变得活跃的部位。

他们发现，脑部前额区的背外侧前额叶皮质能通过判断周边环境和状况是否允许吸烟来调节吸烟的欲望。当产生吸烟念头时，同一区域的眶额叶皮质也积极发挥作用。这两个部位的脑神经共同作用，最终形成了吸烟的欲望。

研究者认为，这一发现将有助于针对烟瘾和药物依赖开发新疗法。


原文链接：

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Dorsolateral prefrontal and orbitofrontal cortex interactions during self-control of cigarette craving

Drug-related cues induce craving, which may perpetuate drug use or trigger relapse in addicted individuals. Craving is also under the influence of other factors in daily life, such as drug availability and self-control. Neuroimaging studies using drug cue paradigms have shown frontal lobe involvement in this contextual influence on cue reactivity, but have not clarified how and which frontal area accounts for this phenomenon. We explored frontal lobe contributions to cue-induced drug craving under different intertemporal drug availability conditions by combining transcranial magnetic stimulation and functional magnetic resonance imaging in smokers. We hypothesized that the dorsolateral prefrontal cortex (DLPFC) regulates craving during changes in intertemporal availability. Subjective craving was greater when cigarettes were immediately available, and this effect was eliminated by transiently inactivating the DLPFC with transcranial magnetic stimulation. Functional magnetic resonance imaging demonstrated that the signal most proportional to subjective craving was located in the medial orbitofrontal cortex across all contexts, whereas the DLPFC most strongly encoded intertemporal availability information. The craving-related signal in the medial orbitofrontal cortex was attenuated by inactivation of the DLPFC, particularly when cigarettes were immediately available. Inactivation of the DLPFC also reduced craving-related signals in the anterior cingulate and ventral striatum, areas implicated in transforming value signals into action. These findings indicate that DLPFC builds up value signals based on knowledge of drug availability, and support a model wherein aberrant circuitry linking dorsolateral prefrontal and orbitofrontal cortices may underlie addiction.

来源：科技日报