功能磁共振成像观察吸烟成瘾者对香烟的嗅觉诱导反应

Functional MRI research of smoker's responses to smoking olfactory cue

目的观察吸烟成瘾者在不同生理状态下以及吸烟成瘾者与非吸烟者接受香烟嗅觉刺激时引起脑功能区的不同激活模式。方法17名右利手受试者(非吸烟对照组5名,吸烟成瘾者12名)完成试验。采用Block设计,EPI采集,以烟卷作为嗅觉暗示任务,纸卷作为对照物。结果12名吸烟成瘾者在戒断状态下面对香烟嗅觉诱导刺激时,左侧额上回(BA8、9、10、11)、右侧额上回(BA10)、左侧额中回(BA8、10、11、46)、右侧额中回(BA8、9)、左侧额下回(BA9)、右侧额下回(BA45、47)、左侧额内侧回(BA6、8、10、11)、右侧额内侧回(BA9、11)、左侧扣带回(BA24、31)、右侧扣带回(BA24、37)、右侧颞中回(BA21)及双侧丘脑及小脑半球激活;在满足状态下,双侧前额叶、双侧小脑半球亦见激活,而其他脑区未见明显激活。非吸烟者面对香烟刺激时全脑未见明显激活,仅1名受试者出现少数小体积激活点,考虑由图像噪声引起。结论前额叶、中脑边缘系统(扣带回前部及后部、丘脑)在通过鼻腔给予香烟嗅觉刺激所诱导的吸烟渴望神经机制中发挥重要作用;在临床型1.5TMR成像设备上,利用鼻腔通路,通过香烟嗅觉诱导刺激观察和研究吸烟成瘾者的相关脑激活区以及神经环路与作用机制是可行的。

Objective To detect different activated patterns of heavy smokers in different states as well as between smokers and non-smokers. Methods Seventeen subjects including 12 heavy smokers and 5 non-smokers （controls） were examined with functional magnetic resonance imaging （fMRI） performing smoking-related olfactory cue tasks. The data were processed with SPM2. These different patterns were compared between the two groups. Results When smokers were exposed to the smoking olfactory cue in the abstinent state, activation was found on the left superior frontal gyrus （BA8, 9, 10, 11）, left middle frontal gyrus （BA8, 10, 11, 46）, left inferior frontal gyrus （BA9）, left medial frontal gyrus （BA6, 8, 10,11）, right superior frontal gyrus （BA10）, right middle frontal gyrus （BA8, 9）, right inferior frontal gyrus （BA45, 47）, right medial frontal gyrus （BA9, 11）, left callosal gyrus （BA24, 31）, right callosal gyrus （BA24, 37）, right middle temporal gyrus （BA21） and both sides of the thalamus and cerebellum. When smokers were exposed to the smoking olfactory cue in the satiated state, activation could be found on both sides of the prefrontal lobe and eerebellar hemisphere, while there was no activation on the other brain regions. No activation was found on the whole brain of the nonsmokers,except for a little small volume active points appeared in individual subjects, possibly caused by the picture noise. Conclusion The Limbic system （cingulate cortex, thalamus） and the prefrontal lobe play an important role in the cue-induced smoking craving approved from the new perspective of the olfactory. It is feasible to research smoking addicts＇ brain activation and the role of neural mechanisms using olfactory stimulation with clinical 1.5T MRI equipment.